View Full Version : Plumbing a new show tank

04-28-2009, 08:51 PM
So I think I've finally decided to spend my kids' inheritance (wasn't much there anyway) and get a new tank and furniture-grade cabinet. Upgrading from a 90 gallon to 125 or 135. BUT, I've got to order a tank that is pre-drilled so that I can change water quickly and easily.

Here's what I'm thinking so far . . . A drain, an overflow, and a fill hole. Hopefully the drawing is understandable. It is the option for ordering a tank with three holes drilled in the back paned, and I would hide the pvc between the cabinet and the wall, and I'll plumb the stub-outs through the wall down to the basement.

The other option would be a pre-fab "corner-flow" tank. Maybe that's better?

My objective is to be able to open the cabinet, turn a valve to drain the tank (80% water change), close it, open another valve and flick a switch to fill.

I would like to hear the opinions of all you Simply do-it-yourselfers! I bet you've got lots of good advice, and since I haven't ordered anything yet, now's the time to ask! THANKS.


04-28-2009, 09:41 PM

You look to be well on your way. I think the difference between drilled back and corner overflow is a bit of personal preference but drilled back provides more space for scaping and fish!

The only thing that is not clear is filtration. I'm assuming you are planning on a separate loop here and this is simply to automate water changes. However, if you are planning on purchasing a custom drilled tank anyways I would suggest that you incorporate the filtration system into overflow/return drilling. You can also put the auto water change design into a filter system and have about the same amount of plumbing to pass between your 1st and basement floors. Under this design I would add more holes, at least one more overflow and possibly a return.

One thing that I do see that is could be a problem is this, how will you prevent siphoning off the entire tank when the mag pump is not running? You will need to put the valve on that system on a normally closed solenoid to make sure that you do not drain your entire tank back down to your barrels. Check valves are another option but not fail proof and of course the larger the head the less reliable the check. If your design has the check in the basement I would worry. The other option is to put that return at the top of the tank with an elbow pointing down and drill a siphon break just below the bottom of the overflow hole. This is a fail safe method for making sure you do not drain the tank but could be a bit noisy at times if not setup correctly.

A forum that is very good for plumbing designs is Monsterfishkeepers.com, specifically CHOMPERS and Pharoah are very good at offering critique on plumbing systems. I would think hard about how you design the overall system and have some patience with the design. I have been working on a design for a 250G for several months now and am just getting to the point where I think every task will be automated and the tank will be power fail safe. These two criteria are very hard to fulfill simultaneously, so take some time and work it all out.

04-29-2009, 05:35 AM

Thanks for the reply. I currently have two canister filters that I plan on using, and those are not included in the drawing. You're right, I was just showing the piping for the water change.

About the siphoning, I used a wierd symbol to indicate a ball valve (manual) under the tank, inside the cabinet. With both of these closed, but with no valve in the overflow tube, I figured there would be no drainage, or siphon.

And thanks for the advise on the other forum, I will definitely check that out.

Hmmm, now you've got me thinking about the whole filtration deal. If I don't use canister filters, then what do you suggest? Would a sump be noisy? Also, I've never understood how a sump doesn't overflow, especially when the electricity goes out, since water always seeks its own level . . . This show tank will be in the dining room, so it's got to blend in, be quiet, and of course, not leak.

Thanks for taking the time to read and respond. -Don

04-29-2009, 08:34 PM
I see. I misread the part about manual. Why would you want to do that? A float switch on your pump in the 55gal barrel would turn the whole scenario into auto fill and drain. You could have everything automated with a few simple additions ie float switch (any sump pump will be fine since it is in your basement). You can use the 80% drain anytime you want to get your hands wet. I would think about it. Everyone here will tell you water is the key to discus and this helps to keep things constant in terms of quality.

Sumps do have more noise but these can be mitigated easily with lids and the proper plumbing. You do have more overflow risk but this can also be mitigated through siphon breaks in the plumbing and a thoughtful float switch here and there.

I would really consider automating since you will be doing a significant amount of work to run plumbing between floors it is marginally more effort to make things easy on you down the road. A bit of reading on the different forums (I saw your post on monster) will yield a lot of interesting ideas. Good luck and keep asking if you have questions. I am no expert but have put in a significant amount of research.

04-30-2009, 12:53 AM
you can have the 20% overflow go to the sump. the volume of the sump should be such that is can handle the the volume from the display. the 80% drain should be on a valve. in my case i also plumbed a hard drain line at 20% in the sump too, just in case. you can use a pond pump or you can use your canisters to draw fresh water out of the sump and return it to the tank. your fresh water out to the tank will equal the amount drained from the 20% hole. but you will have to plumb the 20% hole up near the top, otherwise the tank will sit 20% empty.

04-30-2009, 09:02 AM
agree with doctoes that you want to design your sump to handle all the water. also, i'd strongly consider using gate valves instead of ball valves. my experience with ball valves is that they tend to stick a lot. the gate valves are slightly more expensive but worth it, imo.

04-30-2009, 08:59 PM
Also, I've never understood how a sump doesn't overflow, especially when the electricity goes out, since water always seeks its own level

Picture a pristine aquarium with no holes. Now, imagine a hole drilled 2 inches from top. Imagine this hole is plumbed with a pipe leading to the sump. When the aquarium is filled above this hole, water will rush through the hole until the level drops to just below the hole.

That is how a properly set up overflow is "self limiting." Meaning there is no chance for the entire aquarium to drain. When the sump pump moves water back to aquarium, the water level rises. This "extra" water will flow out of the hole and drain down the pipe into the sump again. And the cycle continues.

In the case where a hole is drilled low in the tank, there is no "limit." In the case of a failure of the check valve or bulk head or whatever, most of the tank will drain out.

That's why I'm not liking the hole for the line from your new water resevoir. There's no need for that to go to the bottom of the tank. Have the water enter from a hole near the top. Much safer, and there is no need for check valves.


P.S. holes drilled in the bottom of the tank for sumps typically involve a "standpipe" that raises the intake to a couple of inches below the top. So the same principal is at work. If the standpipe is removed, then this would be a risky configuration that could lead to flooding if anything breaks.

05-01-2009, 06:09 AM
Tim, thanks for the clarification! I get it.

BUT, if the hole is only two inches from the top of the tank, and the intent is to take out 80% of the water for a big water change, how is this accomplished?


05-06-2009, 09:59 PM
Tim, thanks for the clarification! I get it.

BUT, if the hole is only two inches from the top of the tank, and the intent is to take out 80% of the water for a big water change, how is this accomplished?


What I described are the holes made for unmanned operation of the filters. In other words, these holes are operational whether you are there or not. If the power fails, you're protected because your sump will be able to hold the water that drains.

BUT THAT SAID, you are not only limited to the holes I described. You can in fact put holes lower down to drain the tank during a water change. As long as you understand that using said holes involve manual oversight in case anything goes wrong. Because for these lower holes, there are no 100% fail safes.

For manual water change, you can drill and use lower holes. If you try to do an automated water change system with these holes, then you're back to relying on mechanical safety nets which may sometimes fail.

Hope this helps.

05-06-2009, 11:01 PM
Best scenario for doing massive water changes that are not automated via timers and extra pumps or a drip system is what you have described above for an 80%. However, this has to be manual in my opinion for it to be considered as a realistic option. Too many ways this can go wrong if it is not manual.

To do it manually simply have a hole low down and have it plumbed into the other overflows but put a ball valve between the drilled hole and the connection to the rest of the overflow plumbing for isolation. Open your ball valve and you get an 80% drain. Keep it closed and things are safe and sound. An even slicker solution is to pipe the low hole to 2 places, one up to the height of the plumbing for you other overflows with a ball valve and one straight across like described above. Keep the one closed, and the valve controlling flow up to the water level keep at some comfortable % open. This way you also get overflow out of the bottom of the tank and potentially some extra crap that is lying on the bottom of the tank.