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Thread: Building your own Plywood tank......

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    Administrator brewmaster15's Avatar
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    Default Building your own Plywood tank......

    Hi Everyone!

    I asked one of our skilled members to put together an article on building a plywood tank after I saw the beautiful one he made. Since he was relatively new here, I wasn't sure he'd be interested, but I am SOOOOOO! Glad I asked. Scott aka wall_o_fish here put together an awesome article for us.! I can't thank him enough! and heres the article...now I have another project!

    thanks Scott!!!!

    Building Your Own Plywood Tank
    An Introduction By Scott Taylor
    May 2003
    (Scott is wall_o_fish on SimplyDiscus)


    For some discus enthusiasts, a large show tank—or even a grow-out tank—too often remains a dream due to the cost of larger tanks. Once you get over 80 or so gallons in tank size, the sheer cost of thicker glass and acrylic goes up significantly.
    That increased cost is what led me on a search for an inexpensive, functional, and—if I wanted—nice aquarium. What I found is that aqua-hobbyists have been building tanks made of plywood for years, and using them as both freshwater and marine aquariums.
    The obvious advantage to plywood is that it costs only a fraction of what glass or acrylic does per-square-foot. And when you waterproof it with the right sealers, it holds water just as well as glass-and-silicone or acrylic construction. I made mine over a year ago, and it hasn’t leaked a drop! I also suspect that plywood is a much better insulator than glass is, so your heating bills will be cheaper too.
    They’re relatively easy to build with some common power tools. What’s more, you can suit your aquarium to your own aesthetic standards: do you want to make a inexpensive, functional grow-out tank to keep in your fishroom, or do you want a piece of cherry-veneered furniture, satin-finished for your living room?
    The down-side to a ply-wood tank is that it is, of course, opaque. So you have to build in whatever glass windows you want to view your fish through. I’ve seen side panels built in, but I found myself quite satisfied with the front window. As a friend of mine who is also a professor of media studies said while gazing into the tank: “This is the original wide-screen technology right here!”


    My first attempt at plywood tankmaking.

    The purpose of this article is to describe how to build a tank, but it doesn’t prescribe. That is, I lay out the principles for tank-building but don’t here supply any specific plans. Never fear, though. I do supply lots of links to very specific plans. I want to supply you with how to build a tank—any tank, so you can avoid any big mistakes and then build whatever size of tank you want. If it would help you to get the specifics of tank-building in mind first, jump right to GARF’s plans for a 140 gallon tank. Then come back to the more general points in this article.

    This article is organized into five sections: (1) Plan and Prepare, (2) Materials, (3) Procedure, (4) Considerations, (5) Resources.

    PLAN AND PREPARE
    If you have access to the following list of resources, you should be able to build a tank without much trouble.

    · Patience and a willingness to research and plan
    · One or two people to help you
    · A few common tools
    · Space to build your tank
    · Time to build your tank.

    Patience and a willingness to research and plan
    If you’ve successfully raised discus, you know enough about patience, research, and planning to build a tank, so this shouldn’t be too much of a concern for you. Read this article, then research the links at the end of this article. Then try out lots of different tank-building possibilities in your head and on paper.
    For instance, the first plans I studied gave directions for making a 140 gallon tank that was 8 feet long, 16 inches high, and 24 inches deep (front to back). After looking over numerous other plans for tanks—some up to 800 gallons—I designed and built my own tank at 150 gallons with inside dimensions at six feet long, 24 inches high, 24 inches deep, with a 9-inch extension on one side of the tank for a wet-dry overflow. I also wanted it to be nice enough to have as a show tank, so I made it with a furniture-grade birch-veneer plywood and used trim to hide the screws and rough plywood edges (see picture). I HARDLY recommend something so involved or costly, but my point is that even with the cover, an internal pump, a pine stand, and all the extras I described, I still only spent about $450 on my dream tank! Not bad, eh? A functional grow-out tank could easily be built for much less. And if you’re really going for economy, if you can build lots of tanks at once (two to five would be do-able), you’ll really start saving on the expensive sealer. So if you can find a few other people to build along with you, you’ll be able to build for cheaper and have someone to help you!
    I would also plan the cost of the tank before purchasing ANYTHING for it. I took more than one trip to Home Depot with a pad of paper and my buddy Jesse. In the end, careful planning will help you avoid the larger time- and money-wasting mistakes. Even though you’ll have a list of woulda-coulda’s when you’re done, you’ll still have a functional tank! Then come share what you’ve learned with your fellow enthusiasts here at SimplyDiscus!
    When trying out so many possible plans, you may find yourself continually guessing or re-figuring how many gallons your imagined tank will hold. Here’s a little trick I came across that makes figuring your tank capacity a snap.

    Use the inside dimensions of your tank in the following formula:

    Length x height x depth = cubic inches your tank will hold.

    Then divide the cubic inches by 231.

    Because there are about 231 cubic inches in a gallon, the answer will be very close to your tank’s capacity in gallons. You may want to figure for the airspace you leave at the top of your tank too.

    One or two people to help you
    As mentioned, one advantage to building with someone else is the savings. But it’s nice, too, to have someone to share tools with, to give you an extra eye, and just to have around to keep you on your toes. There’s no way I could have made this tank without my friend Jesse Hallam (in Payson, Utah!) who helped me build the tank and loaned me tons of tools! Buy your friends some drinks and food, ‘cause you’ll want ‘em to hang around! There was one evening where there were more than 12 people just drinking, snacking, and milling around while we built the tank. Better to turn it into a social event and have all the hands around that you need (just be sure you don’t get an off-kilter chiefs-to-indians ratio)!!
    But even outside of sociality, the sheer practicality of working with large pieces of plywood is something to consider too. Although there are some parts of the construction you can do solo, I can’t stress enough the need for extra hands. You need someone else to help you in cutting the larger pieces of wood and in seating the glass on its frame (more on that later). It’s also a good idea to have someone around to help you with many of the time-sensitive operations of building a tank, the most notable of which are the auto-body puttying and the two-step epoxy sealer.

    A few common tools.
    A full-on wood shop isn’t going to hurt anyone trying to build a plywood tank, but you can build one with surprisingly few tools. Essential tools are:
    · A skill-saw, sometimes called a circular saw. You can do all your long, straight plywood cuts if you use a long, straight-edged piece of wood as a guide clamped to the plywood. If you use such a guide, be sure you have a rigid support underneath (not just two sawhorses), or the wood will bend downward.
    · A hand drill, with appropriate bits. You’ll use screws for the plywood-to-plywood joints, so pre-drill the guide holes and use the drill to drive the screws in. You may need to counter-sink.
    · A hand sander. If you use less-expensive plywood, you’ll need to putty any mark that gets in the way of the surface being absolutely smooth, and that means sanding. Most people recommend fiberglass autobody putty for filling in the blemishes. And you’ll need to sand down the putty to a smooth finish when it cures. If you go with a higher tank and want to reinforce the corners with fiberglass tape (the way I’ll describe later), you may want to use a power sander for the inside corners too. If you don’t have one of these already, you can rent them for pretty reasonable rates.
    · A caulking gun for the Liquid Nails and silicone.
    · At least one good square.

    Some other stuff you’ll need:
    · Sawhorses or a large, table-like area to build your tank on. The GARF plans for the 140 gallon tank are very specific about the way to use sawhorses (what they call staunchions).
    · I don’t know if standard furniture clamps (pipe clamps or the fancier hand-ratchet clamps) are essential, but I found them VERY useful in the plywood-to-plywood joints. I used four clamps for the longer joints. If you don’t have any of these, ask around to your woodworking friends. Anyone who makes furniture can’t go without these. I describe how I use them in the “Procedure” section of this article.
    · If you use a skillsaw rather than a table saw for your plywood cuts, you’ll also need some C or similar clamps for fastening your skillsaw guide in place when making long, straight cuts. Another option is using finish nails to hold the guide to the plywood, and then filling in the holes later. (I seem to remember I did this.)
    · Disposable brushes. You’ll want inexpensive, disposable ones because the sealer you’ll use is a two-part epoxy that doesn’t rinse out. If you choose to beef up a higher tank with fiberglass autobody tape, you’ll also use brushes for the resin. I used 12 when building my tank. You should be able to do it with 4 if you apply the paint solo and don’t mess with fiberglass corners. If you want a friend to help you put on the sealer, buy extra brushes. They’re cheap anyway.
    · Various plastic containers for mixing the sealer. I used old cottage-cheese or sour cream containers. You’ll only mix the sealer in small batches (my batches were around a pint to a pint-and-a-half each).
    · Simple auto body tools (a putty knife or two and some sandpaper). You use the putty to fill in any divots, knot holes, or blemishes in the surface of the inside-wall of the plywood. If you use smooth-finished plywood, you won’t need as much or any of the putty. (In my opinion, it’s worth spending the extra ten bucks per sheet on one-side paintable plywood just to have a smoother inside surface for the sealer.) You want a smooth surface because a flat surface means fewer places for the sealer to wrinkle or miss later. Flat = good seal. If you want a pretty tank on the outside, you’ll have to give some thought to getting a smooth finish you can either stain or paint over. But please don’t think it’s absolutely necessary! I’ve seen lots of people’s webpages describing lots and lots of tanks built with inexpensive plywood and a little bit of inexpensive fiberglass autobody putty.
    · If you opt to put autobody fiberglass tape in the inside corners of your tank, you’ll want some putty knives for getting the tape flat. I used disposable ones. I wouldn’t recommend the fiberglass tape unless you’re going with a higher tank or you’re just anxious about leakage. More details on the fiberglassing later.

    Some dream-tools (Far from necessary, but if you know someone with one of these . . . )
    · A router is nice if you want to make a ledge around the top of your tank to rest glass covers on! I didn’t use a router, but instead tacked some ¼” trim around the outside of the top before sealing to form such a lip.
    · If you’ve got one, a tablesaw is a nice alternative to a skilsaw. As long as we’re dreaming, a compound miter saw is nice for trimwork if you want to make your tank pretty.
    · If you’re really fancy, a Roto-Zip. This is sort of like a souped-up jig saw. My friend had one, so I used it for cutting a hole in the front piece of plywood (the window). Many plans call for a pieced-together front window frame, but I got nervous about a segmented frame for a higher tank, as I guessed that a single piece of wood is stronger and less susceptible to leaks. But a roto-zip isn’t necessary even if you’re set on using a single piece of plywood for the front. You can still make the cuts carefully right up to the corners with a skillsaw and then finish the corners with a fine-toothed hand-saw.

    Space to build your tank
    You’ll need a WELL-VENTILATED space dedicated to building the tank. Any two-part epoxy sealer is very toxic stuff. You can kiss your frontal lobes goodbye if you plan on applying the sealer in a poorly-ventilated area. A garage with plenty of flow-through air, a workshop, or a bedroom fitted with reliable exhaust fan directly to the outside should work. Make sure you also have either sawhorses or a worktable of some sort.
    I wouldn’t build this tank in the same area that you keep discus. I know latex fumes are alright, but I wouldn’t subject my fishies to two-part epoxy.

    Enough time to build it.
    I’m not sure why, but building projects seem to take me twice as long as I think they will! Figure lag time for your friends to show up, for coats of sealer and fiberglass resin to cure, for drilling holes, for clamping joints just right, and so on. I waited a full day for the Liquid Nails and silicone to cure. You won’t regret the time you spent when your tank is done.

    MATERIALS
    Other than the tools listed above, here’s a list of materials you’ll need to build your tank.
    · ¾” plywood. Some directions call for AC Exterior. I used both-sides paintable. Both kinds work, but for me the smooth sides were worth the extra ten bucks per sheet. When planning your tank, remember that ¾” plywood isn’t necessarily ¾” thick. Mine was sold as ¾” but actually measured 1/16” less than that. Measure it exactly and draw lots of plans before you make your cut list.
    The basic parts of a plywood tank are:
    § The bottom (L x D)
    § The back (L x H)
    § The sides [H x (D – 2t)]
    § The front (L x H, with the window cut to specifications in bullet below). If you make the front from one solid piece of plywood, make sure you cut the window into it BEFORE you assemble the tank. GARF’s plans make the front from smaller pieces, so you have options to choose from.
    § The glass panel (see specifications below)
    § A brace/top support (dimensions depend on your design). Some plans call for a wood brace. Mine used an acrylic one. I’ve also seen some people use hardware and cable contraptions.
    After each part above, you’ll see the dimensions in parentheses. L = length, D = depth of the tank front-to-back, H = height of the tank top-to-bottom. In the dimensions for the sides, “t” stands for the thickness of the plywood. So, the sides need to be height x depth minus the thickness of the back and front. That way, the back and front sandwich the sides between them.
    Your pieces MUST BE SQUARE, and the cuts must be dead-on STRAIGHT. Use a fine-toothed saw blade and a straight guide for cutting. Get someone to help you brace the plywood sheets during cuts. If you’re using a table saw, get someone you trust to help you. Be careful about relying on the home-improvement store to make accurate, square cuts for you. I spent extra on cuts at the home improvement superstore, assuming that their fancy saw was square. It wasn’t. So I had to trim my pieces a bit at home to get them square. If your pieces aren’t square and your cuts aren’t straight, your tank will leak.
    A premature note on assembly: most plans I’ve seen show the back, sides, and front of the tank fastened to the bottom. That is, they sit on the bottom, not around it. I fiddled with other ways of cutting and assembling the pieces, but the bottom-as-base seems to be the soundest. Since it’ll help you envision what you’re doing as you plan your cuts, I’ve tried to show the names and positioning of pieces in this drawing.



    · A two-part epoxy sealer paint, rated at water-potable quality. Toward the end of GARF’s plans for a 140 gallon tank, you’ll find some detailed brandnames for paints. I also supplied a link here for the supplier of the paint I used to build my tank. (If you know of other great suppliers, share the info with the SimplyDiscus community!)
    · A panel of glass. The piece of glass is a relatively expensive part of your tank. Make sure you buy a sufficiently-thick piece, and get the dimensions right for the tank’s interior measurements! I’ve read of and seen that some people have recycled leaker tanks by using the long panels of glass in plywood tanks. Do you know someone with a leaker tank sitting empty in their garage? Make ‘em an offer!
    The glass thickness will depend on the tank’s height and length. I’ve included links to a handy chart for estimating your own thickness needs. If your tank is 16 or fewer inches high, you should be safe with ¼” plate glass. My tank was 24” high and used 3/8” thick plate glass. But check the charts, and don’t give in to the temptation to buy thinner glass than you need. It’s better to err on the side of safety than lose a tankful of discus to a break.
    An important note on glass dimensions: Make sure that two or more inches of glass extend past the edges of the front window. So, if my tank window is 18” high, the glass should be AT LEAST 22” high. Also remember that you’ll need to figure glass dimensions by the inside dimensions of the tank, minus some wiggle room for insertion. GARF’s plans (in the links) allow ½” extra length (so ¼” on each side). I gave myself a FULL INCH for wiggle room (so ½” on each side). I knew that glass sheet would be heavy, and I didn’t want my clumsy moves to put a divot in my painstakingly sealed inside coating! You’ll also want to figure whether or not your tank’s center brace may intrude upon the glass’s height the
    You may want to consider spending the extra money on having the edges finished. I didn’t finish mine, and got more than one zinger of a cut on my forearms and knuckles. You can “hide” the sharp edges by gooping them with silicone once you it’s in place, but it’s scary working with sharp glass edges, even with leather gloves on. You touch the glass during installation more than you would think! You can finish the edges yourself too with sandpaper and a block (or emery cloth and a block).
    I’ve read accounts of people using safety glass, but I didn’t use it. Plate glass was my choice.
    · A box of two-inch screws. Use exterior screws if you don’t plan on painting or varnishing the exterior, although I HIGHLY recommend painting or varnishing the exterior. In fact, if I were making a growout tank, I’d put a coat or two of the sealer on the entire tank, since you’ll be dripping water all over when you do water changes. And you don’t want humidity getting into the wood. I even varnished the bottom of my tank.
    · Liquid Nails. I used the waterproof kind, for obvious reasons. I think I used two or three tubes of the stuff. It’s cheap enough to err on the side of excess; better to have half a tube leftover than to run out halfway through gluing a plywood joint.
    · Silicone. I wouldn’t bother too much with the spendy “aquarium safe” silicone. My opinion is that the regular clear silicone available at just about any home improvement store in tubes made for caulking guns is pretty aquarium safe. Just make sure it reads “100% pure silicone,” and steer clear of colors or mixtures. I used two tubes.
    · Glass cleaner from a glass supply store. Get the kind that professional glass workers use rather than simple window cleaner. The pro stuff leaves little or no deposits behind, which is exactly what you want for your window’s seal.
    · Paper towels, etc. You’ll get lots of goop on your fingers from the Liquid Nails, Silicone, varnishes, sealers, etc.

    PROCEDURE
    This section assumes you’ve planned your tank, made lists of everything you need, gotten your wood, cut the wood to dimensions, and gotten your glass, sealers, etc.
    A repeat precaution: most plans I’ve seen show the back, sides, and front of the tank fastened to the bottom. That is, they sit on the bottom, not around it. I fiddled with other ways of cutting and assembling the pieces, but the bottom-as-base seems to be the soundest.

    My process followed GARF’s in the larger motions:
    · First, fasten the back to the bottom,
    · Second, fasten the sides to the bottom and back,
    · Third, fasten the front to the bottom and sides.
    · Fourth, attach the brace in the manner most appropriate for your style of brace. (More on braces later.)

    I’ll here only offer my variations from the GARF plans so people can compare another way that works. My process differed from GARF’s in four ways:
    1. I used pipe clamps rather than the customized stanchions there described (stanchions are like sawhorses), although I can see the wisdom in making the stanchions if you’re going to make more than one tank. Fastening with pipe clamps requires the help of at least one other person.
    2. After gluing and screwing, I also joined the inside corners of my tank with fiberglass tape and resin. I wanted extra strength on the corners because I added extra height to my tank (24” high rather than 16”), but I have no idea if my precautions were actually necessary. Anyone had success with plain glue-&-screw joints for higher tanks?
    3. I used fiberglass resin (just the resin, not the fiberglass itself) as an under-layer to the two-part epoxy sealer, but I now think that this precaution was unnecessary, if not an aesthetic mistake. More on that later.

    I’ll now expand on the list of three items above.

    Pipe-clamping requires more than one person. If you’re working alone, GARF’s method would probably be the way to go. It’s also a good idea to keep a couple extra bits on hand.
    I used the following general steps in making plywood-to-plywood joints:
    1. Clamp and align wood pieces without glue.
    2. Drill pilot holes. Counter-sink if desired.
    3. Unclamp and set up guides for later repositioning.
    4. Apply glue (I used Liquid Nails).
    5. Re-clamp loosely, using guides to realign pilot holes.
    6. Drive screws.
    7. Remove clamps and promptly wipe off excess glue.
    8. Drill and drive any other necessary screws that clamps may have blocked.

    To expand those steps, I’ll describe how I joined the back piece to the bottom piece.

    To fasten the back to the bottom, first make sure that both wood surfaces in the joint are flat and clean. Sand off any aberrations.
    Lay the bottom face-down onto a free-standing worktable, with the bottom’s working edge extending past the table by a couple inches. You want the side of the bottom that will eventually be inside the tank to be face-down on the table. Have someone help you raise up the back piece into its proper position against the bottom piece (make sure you have the correct side of the back facing the tank’s eventual inside). Loosely pipe-clamp the back in place. You’ll need at least two clamps for this; I used three. Nudge/adjust the pieces to make sure that the back and bottom are flush on both ends and all the way along the plywood-to-plywood joint. Get the edges to meet as exactly as you can; I had to keep telling myself that I’m not mental to worry over 1/32 of an inch! Once you have both pieces in place relative to each other, clamp them more tightly in place, so they won’t budge as you’re drilling.
    Now that the pieces are clamped in place, you’re ready to drill pilot holes for the screws. If you haven’t drilled screw pilot holes before, choose a drill bit that’s the same size as the center shaft of the woodscrews you’ll be using. (If you have to err on the size of the bit, it’s better to go a hair smaller than larger, since you want to provide enough wood around the pilot hole for the threads to bite and hold into.)
    I drilled the holes as deep as the screws would reach into the wood, minus about an eighth of an inch. Many of the directions I’d read online (GARF included) placed the holes about three inches apart. I went four inches, and I’m wondering now if it wouldn’t hurt to go as far as six inches apart. My suspicion is that the Liquid Nails does more of the actual holding than do the screws. Let us know if you have any experience on screw spacing.
    Drill the holes as straight and as on-center as possible. The clamps will block you from drilling a few of the holes, so you’ll have to drill those later, once the clamps are off. When you’re placing the holes, remember that screws driven from different directions can run into each other at the bottom inside corners of the aquarium! Plan ahead so you don’t split your wood with colliding screws. I’ve seen some plans call for shorter screws at these corners. I think I just kept the screws about 3” from the corners, and relied on the Liquid Nails and fiberglass to keep the bottom inside corners intact.



    If you want to counter-sink the holes, do that now, before you unclamp the pieces. (I chose to counter-sink, since I had a birch veneer. You may not want to mess with it if pine will be soft enough to “give” with the screw’s head. Try a few test pieces first though!) Now, loosen the clamps, and lower the back piece. Before you apply glue to back piece, you’ll want to create a guide for re-positioning the back exactly into place. Choose two pilot holes near the ends to drive a screw through just enough to have the screw point extend past the surface by about 1/8 of an inch. Make sure you choose pilot holes that won’t interfere with re-clamping. This protruding point will allow you to find the respective pilot hole match-ups, and thus re-align all the holes. I’ve also heard of people simply drawing some light pencil lines across the two clamped pieces of plywood before unclamping. Then once the glue’s applied, just re-align the pencil marks. Do whatever works.
    Put a bead of Liquid Nails along the appropriate edge of the back piece. It’s better to use too much Liquid Nails than too little, but I’d recommend a preliminary squish-test on some scrap wood to get a feeling for how it’ll spread out. Now that the pilot holes in the back are glued over, you’ll have to rely on your eye and on slowly screwing the pipe clamps so that the back is raised into position. (It’s really important to have good communication with your building mate as you reposition the pieces.) It’s delicate work finding the guides so that the pilot holes will line up. You’ll find that the Liquid Nails sets quickly, but it can also act a bit as a gliding lubricant before it sets up. Don’t be heartbroken if you smear a bit of Liquid Nails where it shouldn’t go; you can clean it off later. You WON’T tighten the clamps down as tightly as they were before, since you’ll want a slight “give” to the joint so that the pilot holes can realign themselves. Now drive the two guide screws all the way in; you’ll see the pieces re-align slightly as you do. I next drove a screw near the middle of piece, just to do large alignments first. Then drive in all the screws ‘til the joint is nice and secure.
    Once you have the joint secured, remove the clamps and quickly wipe off excess Liquid Nails from the inside and outside of the tank. DON’T wait ‘til later to wipe off the Liquid Nails. If you do, you’ll have to sand it off instead of wiping it. Ugh!
    If you missed any screw spots because of the clamps, drill and drive those now.
    If you’re not clear on creating the plywood joints, or if you’re just nervous about screwing it up, practice on some scrap pieces first.

    With the bottom still face-down, scoot a working edge to one end of your table so you can repeat the above process to fasten in one of the sides. The sides are extra fun since you have TWO surfaces to pre-drill and align. Make sure that the side is tight against both the bottom and back. The steps are still the same though:
    1. Clamp and align without glue.
    2. Drill pilot holes. Counter-sink if desired.
    3. Unclamp and set up guides for later repositioning.
    4. Apply glue.
    5. Re-clamp loosely, using guides to realign pilot holes.
    6. Drive screws.
    7. Remove clamps and wipe off excess glue.
    8. Drill and drive any other necessary screws that clamps may have blocked.

    If your table isn’t longer than the tank, you’ll be able to put both sides on with the tank face-down. If the table is longer, you’ll have to turn the tank over to put on the other side. But make sure you have at least one side screwed and glued on tight before you attempt to turn the tank over. The side gives extra support to the back-to-bottom joint.
    Before you add the front panel, remember to cut the window into the panel if you’ve decided to make the front all one piece. If you make it from separate pieces, see GARF’s plans for assembly.
    After you have the back, sides, and front screwed and glued in place, with all the excess glue wiped off, take a breather! You’ll want to let the Liquid Nails cure for a full day, anyway.

    I initially thought that I shouldn’t attach the plywood center brace at this point; GARF’s directions tell you to wait ‘til after installing the glass. I believed them, figuring that you can’t attach the brace because it would impede the glass installation. And I didn’t want to install the plywood brace later because I’d have already sealed the plywood, making a good joint between the brace and aquarium body difficult. But I’ve since changed my mind on it. I’ve done the math (the old A2 + B2 = C2 bit for figuring the hypoteneuse of a triangle), and I think it’s possible to install and join the brace before sealing the plywood and then still fit the glass in. The handling would be a little trickier, but I think it could work.
    But anyway, at the time I didn’t install a brace at this point. And since I didn’t at the time understand how to properly join the plywood brace, I designed my own acrylic brace, which I’ll describe later. For your own tank, do your research and then decide on the brace that works best for you. For my next tank, I think I’m going to try a pure hardware brace.

    As noted, my tank was higher than GARF’s 140 gallon tank, so I decided to reinforce all my inside corners with fiberglass ribbon and autobody resin. I got the idea from a very detailed and very sturdily-built tank I’d read about online. But now I simply can’t find the site again! I’m not so sure that my fiberglass reinforcements were necessary, since GARF’s 500-gallon tank doesn’t use fiberglass ribbon either. However, when I build my next tank, I’m still going to use the ribbon again. The Krib’s Q&A page on plywood tankmaking describes a project where a guy tried to cover the ENTIRE inside of the tank with fiberglass. He regretted that effort, and I think I would too. The surface would become very rough and make a tough surface for the glass to seal to.
    However, I had an autobody pro (Jesse!) teaching me how to apply the four-inch-wide strips of ribbon in the corners. If you decide to go with the fiberglass ribbon corners,
    · Practice on a scrap joint first until you can get a nice flat fiberglass corner.
    · Make sure that the plywood surface is clean first.
    · Make sure that you get the ribbon to stick down nice and flat.
    · Make sure that you use just enough resin both under and on top of the ribbon. Don’t overdo the resin or it’ll run and drip.
    · Once the resin/ribbon cures, sand down any rough points sticking up. Take extra care along the surfaces that’ll eventually bond with the glass.
    So far, my tank hasn’t leaked a drop. But I haven’t got a “control” tank to compare it to, so I can’t say how much its water-tightness has to do with the fiberglass corners.

    Another way my tank differed was that I decided to coat the entire inside of the tank with the same resin I used for the fiberglass ribbon. Initially, the resin coating was simply for an added layer of protection and waterproofing. But I now believe that this decision was unnecessary and most likely a mistake. As the resin began setting, I panicked and I applied the resin too heavily. The drips we so bad, you could see them under the sealer. I could have sanded them off, but I was too lazy/anxious to get done at that point. Next time, I won’t use resin under the usual sealer. It does supply a nice, tough under-layer for the sealer, but it sets so quickly that it’s tough to do it right. Maybe I’ll change my mind when the time comes, but I dunno.

    Now you’re ready to apply the two-part epoxy sealer. Again, GARF’s plans are pretty thorough on this process. My main tips are:
    · WORK IN A VENTILATED AREA
    · Use cheap, disposable brushes
    · Mix only a little at a time (enough for one coat). Once it’s mixed, it begins curing, so any unused sealer goes to waste
    · Apply four coats, and make sure you get into every nook and cranny—anywhere that water will touch needs sealer! I may even go more than four next time, if I have extra sealer left over.
    · I found that it was better to go with many thin coats than a few thick ones, since the sealer can drip. The sealer has a VERY low viscosity compared to latex paint, so it drips easily. Drips make your tank not-so-pretty.
    · You can apply the next coat of sealer as soon as the previous one is dry to the touch DON’T rush it. If the previous coat is still tacky, give it time to cure.
    · Decide beforehand if you’re going to apply the sealer to the tank exterior. I’d recommend covering it with something if only to keep it moisture-protected, whether it’s sealer or latex or urethane or what.

    Okay! Assuming your tank is assembled and sealed, it’s time to install the glass panel! I follows the GARF 140 directions pretty much to the T, except that I stole one idea from an online account I read since my glass was a bit heavier than the usual ¼” thick panel. If you have a ¼” thick panel of glass, I’d just wear some leather gloves and put it in place by hand unless it seems too awkwardly heavy to do so.
    For heavier pieces of glass, prepare two “pedestals” made of scrap plywood or 1x6s (or whatever). Make them about a foot high, so they can hold your glass panel “suspended” inside the tank, up above the prepared sealer surface.



    You can then reach under the pedestals with your caulking gun to apply the silicone. Use LOTS of silicone. I applied a VERY FAT bead of silicone—about ½”—along the center of the prepared sealer area. I seem to remember I went through about one and a half tubes of silicone. I’m pretty sure that glass and plywood have at least mildly different temperature expansion rates, so silicone will be your “buffer” for these differences. It’s much better to wipe off excess silicone that’s gooshing out around the edges of your glass than to have just a thin strip holding your glass to the sealed plywood.
    Once the silicone is in place, have a friend help you to promptly lift the tank up “into” the glass panel. That is, your prepared sealer surface will be lifted up to meet the glass supported by the pedestals. (I say promptly ‘cause if you wait too long, the silicone will begin to form a “skin” on it. Bad for your seal!) Communicate with your friend so you can lift very carefully. Watch the glass panel to position it just how you want it. Leave yourself enough room for whatever kind of brace you’ve planned for the top of the aquarium, and then leave space evenly around the other edges of the glass.) Silicone may goosh out a bit. That’s okay! Knock the pedestals out from under the glass and lower the tank again. Wipe up any excess silicone inside. I’d add more silicone inside around the glass edges, but do that later. No use impeding the drying with extra layers of wet silicone right now!
    If you had silicone goosh out under the glass, use the pedestals to now support wood rather than glass, and have your friend balance the glass as you wipe the joints as clean as you can. If you smear silicone on the glass, you can scrape it off later with a razor blade, or just leave it if your tank is a simple fishroom growout tank.
    Now, place the tank flat and window-down on your worktable or on the floor. Place some heavy books on the glass panel to keep the glass pressed well into the silicone. Don’t go crazy with the weight though. No cinder blocks or anything. Books worked fine for me.
    Then, go change water! Just give the silicone a day to cure. You might want to air the room out too, since that silicone starts smelling pretty vinegary. Once it’s thoroughly cured, add more silicone around the glass edges inside. I covered up some potentially-sharp edges this way.
    If you prepped the sealer surface well, thoroughly wiped the glass with a good cleaner, kept your hands clean, and used a healthy amount of silicone, the odds are that you’ve got a good seal. Hooray!

    After siliconing the glass in place, I’d go back to following GARF’s plans. Their plywood brace would, I think, be very functional. If you want to use their brace plan (and I’d recommend it, since the guy has been making tanks forever like that), then go for it.
    I decided to make an acrylic brace, because at the time I couldn’t figure out how to use the plywood one (as previously discussed). I also wanted a clear brace, so my light could shine through it. Here’s a rough 2D drawing of my brace.



    In the drawing, the distance from A to B is exactly the outside measurement of the tank from front to back. Here’s a 3D picture of the corner I circled above.



    Here’s another pic of the same corner, this time in place on the front frame.



    In the pic above, that little strip of acrylic actually protrudes a bit in front and in back. If you’ve got questions about how it actually works, I can send you a whole passel of photos of it by email. If you’re worried about aesthetics, you can cover the protrusion when designing the tank cover. I covered it with the handle. But that’s hardly necessary if you’re building a growout tank. Well, the acrylic’s not necessary in that case either.
    I used ¼” acrylic for this brace, but I think I’ll use 3/8” next time, just ‘cause ¼” starts to sag after a while. Flat sheets of acrylic tend to sag after a while if not braced with perpendicular pieces. Experience is a heckuva teacher.
    If you plan to work with acrylic, do some reading up on it first so you don’t waste expensive acrylic! There’ve been some very informative discussion threads on our very own SimplyDiscus on acrylic working. Here’s one with a very informative write-up by Ralph. Discusgeo recently posted a link to making an entire tank out of acrylic. (Has anyone done this successfully? I can’t seem to find acrylic at the same per-sheet price they’ve mentioned in the article!) There’re quite a few tips for acrylic working in that article. There’s also a Yahoo group dedicated to aquarium building that can direct you to links with tips on acrylic working. DON’T try to drill, cut, or glue acrylic ‘til you’ve done some research!
    I want to re-emphasize here that a acrylic brace IS NOT NECESSARY, and I wouldn’t even say that it’s the preferred way to go. Make your brace out of whatever works for you. I think I’m going to try making mine out of hardware next time. The only reason I don’t use the plywood braces is that I want to be able to use a 48” strip light for the tank’s top openings.
    After you’ve attached the top brace, you have a plywood tank! I let mine just sit for a while before I put any water at all in it—four days or so. But you’d probably be good with two days.
    Of course, you’ll need a stand, but I won’t go into details of that here. My tank was a simple 6x4, 4x4, and 2x4 assembly. GARF has some great tankstand plans too; just go dig around and find them. If you want to, adapt their plans to make your own. Both SimplyDiscus and DAAH have some great ideas in the DIY sections on tankstands too. Just remember that plywood tanks need flat support from underneath in the say way that acrylic tanks do: provide level, even support for the entire bottom. (Glass tanks, in contrast, just need support on the edges.) Just keep it level and strong, and provide support underneath.
    I took two days to fill the tank just to test it. Half full one day, all the way the next. Better only 75 gallons on my floor than 150! Fill it with water that’s near room temperature.


    CONSIDERATIONS
    Now that you’ve read and compared some detailed plans for plywood tankmaking, here are some common questions and issues, or alternatives to building. Many of these are MY questions and issues too! So drop a line in a discussion thread if you’ve got answers or ideas!

    Durability
    I recently called GARF to ask them about some finer points of applying the top brace as described in their plans, and they informed me that GARF has mostly moved to making shallow acrylic growout tanks for their live rock. I asked why, and they told me that after ten or so years, the plywood tanks began leaking. I didn’t find out if the tanks began leaking in the glass-to-plywood seal or in the plywood-to-plywood seals since they didn’t have any “old timers” around I could talk to. Has anyone had experience in the longevity of plywood tanks?

    Glass vs Acrylic Window
    You may wonder whether you can use an acrylic sheet for the window rather than glass. I’ve heard (and had) many observations that acrylic doesn’t seal well with silicone, but I’d love to hear of methods of fixing acrylic windows to the sealed plywood, since I’d love to use a lighter material for my next building project! If you know of success stories, please email them to me, or start a thread about it here on SimplyDiscus!

    A Routered Top
    Next time I build a tank, I’m going to try routering a ledge into the top inside edge of the tank before I seal it so I can rest a glass or acrylic cover on the ledge. Anyone tried this?

    The 4x2x2 Tank.
    A discus enthusiast in Utah once emailed me a simple jpg plan for a simple 4’x 2’x 2’ plywood tank. That’s roughly 100 gallons. I’ve lost the file, but the elegantly simply plans pulled off a tank out of a single piece of ¾” plywood. You’d need thicker glass, but the simplicity of the idea is beautiful! One piece of plywood!

    Wall o’ Fish!
    I’ve seen some links off of GARF that shows how to make a literal Wall of Fish! The basic idea is stacking the tanks one atop the other with extended tankstands. I’ve also given some thought to making GARF’s standard 96x24x16 plywood tanks with sub-tanks built into them via a center divider (in other words, another side panel placed in the middle of the tank). Although I’d love to have a stack of two or three such tanks in my living room, my wife isn’t quite as keen on the idea. So, the real Wall o’ Fish will have to come true when my fishroom does: after I’m done with school! (I’m still a poor student!)

    The Planted Tank
    If you’re into planted tanks but you don’t wanna spring for the compact fluorescent lights, build a shallower tank. The light diffuses less with shallower water. The 140 gallon tank at GARF is only 16” tall, so a double-strip fluorescent fixture fitted with T8 bulbs may be enough light to get a nice planted tank going. Has anyone out there pulled this off?

    The Brace
    I’ve discussed options for using GARF’s plywood brace, and an acrylic brace that worked. I’ve also seen some people use hardware (bolts with eyes, cables, and/or steel plates) for the center brace. It seems like a nice idea, especially if you can use corrosion-proof hardware and fit a threading into it somehow to be able to slightly adjust the tension. Has anyone done this successfully? Got pics?

    The Sealer
    I’ve heard reports and read some discussion threads on the possibility of using polyester resin or fiberglass resin to seal the tanks. (Are the two resins the same thing?) I’ve read some experienced tankbuilders’ cautions against it due to leaching toxins into the water. I can’t say I have any experience that support their cautions simply because I’ve not tried it. Anyone have anything to report? The two-part epoxy sealer is one of the most expensive parts of your tank, so it’s understandable that people would search for other means of sealing the tank. Any input?

    Protecting the Sealer
    I read of one guy putting a piece of 1/16” acrylic on the very bottom of his aquarium in order to protect the sealer. I was tempted to do the same, but didn’t due to the cost. I’ve since had a fine gravel in my aquarium and no significant wear and tear to the sealer. Anyone else got input on this?

    Gnawers
    If you like plecos, be careful! I’ve seen some heavier-duty plecos mar the inside surface of an acrylic tank with their gnawing. Those same fish will make short work of your plywood tank. I did have milder such fish—sturisoma aureum—and they didn’t harm my tank a bit. The bigger ones will. Does anyone have a species list of red-alert gnawers to share?

    Exposed Wood
    I haven’t read anywhere that you MUST seal up exposed external plywood, but it makes sense to me. Water changes can be sloppy sometimes, and fishroom humidity is a real thing. I did my tank with simple urethane, and it hasn’t shown any signs of moisture absorption.



    LINKS

    The Geothermal Aquaculture Research Foundation
    http://www.garf.org/
    Go to the lower-left-hand frame of this site and click on the “how to pages” link. It should drop down a menu of further options. Choose “aquarium construction and tips.”

    GARF’s plans for a 140 gallon tank
    http://www.garf.org/140.gallon.html
    These were probably the most informative for basic tank construction ideas. It seems like the best plan for building economical grow-out tanks.

    GARF’s account of building a 500-gallon tank
    http://www.garf.org/news25p2.html#HUGE
    This article is what got my mind turning about adapting the basic 140 gallon plans to suit my own designs. Browse around the how-to pages, and you’ll also see a neat series of photos for stackable system of 4’x2’x2’ plywood tanks, used for growing coral. (But who’s to say you couldn’t build the same thing for discus?)

    The Krib has a nice page of plain-text Q&A on plywood tankmaking.
    http://www.thekrib.com/TankHardware/wood-tank.html
    It’s from this page that I got the idea to use woven autobody fiberglass ribbon and resin around the inside corners of the tank. It also has lots of woulda-coulda’s from experienced tankmakers on many different aspects of tank-making (resins, sealers, fasteners, etc), so read up!

    A Yahoo group dedicated to aquarium building.
    http://groups.yahoo.com/group/aquariumbuilding/
    You have to get a yahoo account (free) to access this group’s information, but it’s a very useful site. Skim through all the messages, and check out the links! There’re some very informative and cool sites. This site covers many different methods of building aquariums—not just plywood.



    I bought the two-part epoxy I used from Aquatic Ecosystems; search for “Sweetwater paint.”
    http://www.aquaticeco.com/
    They’ve even got it in different colors. (I chose light grey, but I saw that the big tank at daah was done with black, and looked pretty neat too for a planted tank.) Don’t think you have to get your sealer from aquaticeco though. I’ve seen that many others have gotten water-potable sealers elsewhere. The catch is that most suppliers sell it in five-gallon kits (four parts paint, one part activator) for larger applications (like the inside lining of a watertower, say). If you can get three to five people to build tanks with you—or if you make a bunch at once—that’d be a more economical way to go. I used one gallon and a bit (1/5th, say) left over. Oh, plan on a flat extra shipping charge for a special hazardous materials handling fee! It was about 30 bucks extra, if I remember right. But if you ordered for many people, the flat rate would start evening out a bit.

    But how thick do you need to make the glass? I found a handy chart for figuring the thickness you’d need for plate glass, based on height and length of the aquarium.
    http://www.thekrib.com/TankHardware/...thickness.html
    If that link’s down, you can find the same chart at this alternate link.
    http://www.thesea.org/captivesystems...glassthick.asp
    If you must err on the glass thickness, though, err on the side of too thick rather than too thin. Thinner glass is cheaper, but don’t give in to the temptation to make the glass so thin that it will break!

    Mr 4000’s website is about, well, a homemade 4000-gallon aquarium, made from concrete.
    http://www.mr4000.com/
    The site has some photos of the tank’s construction. I’m not sure I’d want to do water changes on that tank.

    Believe it or not, I also found lots of ideas by simple web searches with google and lycos.
    http://www.google.com
    http://www.lycos.com
    I pilfered my idea for fiberglassing the corner joints of my tank from an account I found in just such a way. It was from someone making a very large plywood tank (over 500 gallons).

    I didn’t get into do-it-yourself links for lighting, siphons, or overflows at all. They’re out there though.
    Last edited by brewmaster15; 11-18-2014 at 12:53 PM.

  2. #2
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    Default Re:Building your own Plywood tank......

    Thanks Scott and Brew. What an excellent article!!!. I'll get my pen and paper and start drawing. A 500 gal. Wild tank with rocks and plants. Swim with the wilds in my basement. My own Amazon at home. Hope my insurance company doesn't know what I'm doing.
    Jimmy.

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    Default Re:Building your own Plywood tank......

    Thanks for posting the article, Al. It looks great!


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    Default Re:Building your own Plywood tank......

    By the way, if you'd rather have this article as a Word file to keep on your hard drive, just send me your email in a message and I'll send it to you.

    Please feel free to post your own experiences, ideas, and questions for tankbuilding! I'm sure there's tons of experience on the board for this topic!

    scott

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    Default Re:Building your own Plywood tank......

    Scott,

    that was without a doubt one of those descriptive and well writen articles I've ever seen on the subject.

    Glad to have you as a member here, and I hope you don't mind if I pester you a bit when I decide to build one of those!

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    Default Re:Building your own Plywood tank......

    I won't mind at all if you want to pester me with questions, Jason. Just be sure you post pics and comments of your project to the boards!

    By the way All, DAAH recently posted this excellent article by the late Jim Quarles. I immediately recognized it as one of the articles I read very early on in my research. It was the one that gave me the idea to use fiberglass in the plywood corner joints. I highly recommend the article.

    http://daah.info/index.php?board=28;...;threadid=2012

    scott

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    Registered Member Ardan's Avatar
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    Default Re:Building your own Plywood tank......

    Excellent Write up!!


    Thanks for sharing! 8)

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    Default Re:Building your own Plywood tank......

    Good job Scott!

    I had the pleasure of "reviewing" the article before Al posted it....You did an awsome job!

    Tony

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    Default Re:Building your own Plywood tank......

    I see a big tank in my future...
    Did you see that 4000gallon monster! How Cool would that be full of discus with an Amazon setup?!!!

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    Default Re:Building your own Plywood tank......

    Much thanks to all for the kind words. Please overlook the typos, point out the foggy parts, and supply your own links and ideas!

    Yeah Giroux, i'd love to have a huge amazonian biotope tank, although 4000 would be a beast to do water changes on! Maybe something closer to 300 would be plenty for me! :P

    I'll be building another tank around christmas or so this year, so I'll take pics of the project!

    scott

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    Default Re:Building your own Plywood tank......

    Not for me!!!!!!!!!!!

    Too much other stuff to do around here.

    John

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    Default Re:Building your own Plywood tank......

    Thanks Scott. Great article, can't wait to start on mine.

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    Default fiberglass

    BTW All, I've found many, many reports that plywood tanks eventually separate at the plywood-to-plywood joints, especially at the bottom corners of the tanks due to the outward weight of the water. However, Jim Quarle's article (recently posted at DAAH under their DIY section) notes that his tank lasted over ten years without leaking a drop due to fiberglassing the inside of the tank. I'm guessing that fiberglassing the inside corners (at least) holds the wood together and the joints tight. Mine didn't leak at all, but then again it was only a year old

    I just know that when I make my next tank, I'll be using fiberglass tape on the inside corner joints before applying sealer.

    scott

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    Default Re:Building your own Plywood tank......

    Holy Cow!

    and the Oscar for best/most detailed article goes to ...

    Scott!!! ;D

    Chong

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    Default Re:Building your own Plywood tank......

    Fantastic article Scott!

    I know a fish keeper in my city that has made himself a 700 gallon show tank out of plywood. Most of his tnaks are of this design (total 2500 gallons) and he can confirm their durability. And you can get away with thinner glass (and of course less cost) than you would normally need for an all glass tank of similar size. He uses the silicone trick in the corners of the plywood joints on top of the cured waterproof paint to help prevent leaks down the road.

    To see some of his set up look here:

    http://www.asw.ca/Aquarium_Society_o...ris_biggs.html

    Daniel

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