help setting up a big tank

[JDS]

Hi everybody first-time poster. And I have a few question in regards to converting my big reef tank into a planted discus tank. My first two questions will revolve around lighting and filtration. I was wondering if it's possible to use a 400w metal halide suspended high enough over the tank which I will make an aluminum reflector that goes the total length of the tank. My question is will it produced enough light for the whole tank or will it be too dark on both ends. And by the way the tank is 265 gallons. My second question is should I use a big canister filter or a wet and dry. Any input would be greatly appreciated.

[ChloroPhil]

First off, welcome to Simplydiscus! You chose the right forum for your first post..

As far as your light, a MH pendant really produces only enough light for a 2' section of tank. If I had a 6' tank I'd put 3 bulbs over it.

Secondly, 400w is a huge amount of light for one bulb, usually 125-175 is more than sufficient.

Third, I would definately use a Wet/Dry on that tank, possibly even two.

Again, welcome! If you have any other questions please ask them, one of us around here will know the answer.

Best,
Phil

[JDS]

thank you for the reply .And I assure you I will have many more questions. Regarding that MH I was under the impression that a MH had a three foot spread. It's not a conventional Pendant light. I have the ability to make a different type of reflector for it so it won't be a pendant style. But you are right about the 400w light it is probably too much. But since I have all this equipment that I can use I'm trying to figure out if I can actually use it. Would 2- 250w MH work instead. I think if I arranged the lights high enough it might work. Being the tank is 30 inches tall. What do you think.

[Debbie]

It might work, but the higher you hang the pendants the less light will reach the bottom of the tank. You would be better off with 3 pendants in a tank of that size and depth. If you only do 2 you may be able to get away with lower light plants.

[JDS]

Thanks DEBBIE. I think I'll try and see if I can configure the lights low enough to make it work. I will just have to see what it looks likes. If it doesn't work I will pick up another pendant. I'm just trying to save a little money where I can and use the stuff I already have. And sense the tanks not set up yet anyways knows the time to experiment.

[ChloroPhil]

You can probably make them stretch with a really good one-piece reflector. I agree with Debbie though, three would be better.

With two you're going to have some areas with good shade. There are plants which will do just fine under those conditions, but it will take careful planning and plant selection on your part. I'm pretty sure your fish won't mind the shade.

If you want to add a little more light in between the pendants a couple Powwer Compact fixtures wouldn't hurt as suppliments.

As far as MH being appropriate for a 30" high tank, they're about the only thing that is. You're likely going to be better off with 175w bulbs about 12" off the water in this case.

Something like this should work well:

---PC--- ------------MH----------- ---PC--- -------------MH------------- ---PC---

You wouldn't need very strong bulbs, 55w should be sufficient for the little extra zing.

Best,
Phil

[JDS]

You know you're probably right. I don't know what I'm thinking. In reality I have to get new bulbs anyways because I know that 10000k probably won't work well for plants.

[ChloroPhil]

10,000K will work just fine. I've had some great results at that spectrum. The range of 5300-6700K is more balanced and looks more like daylight to our eye, but 10,000K won't be a problem. Intensity and coverage are the more important factors.

[JDS]

That's a surprise. Never did figure that plants wouldn't mind that spectrum. And thanks a lot you keep ruining my rationale to get new lights.

[ChloroPhil]

How about this?

Over time the phophors in your bulbs change chemical composition so you need to change bulbs every year or so.

[Debbie]

That light arrangement Phil suggests would work well. How old are the MH bulbs that you have? Since you are not new to MH you know that the spectrum changes over time. I have only used MH for a reef tank so I'm not sure if the bulbs need to be changed for fresh like they do for reef (at least yearly). What do you think, Phil?

[Debbie]

Never mind. I think we were typing at the same time Phil!
that answered my question before it was asked....How do you do that

[JDS]

I think what I'm probably going to do is Run 3 175w MH. I think 3 250 watts might be a little bit of overkill especially in the beginning when the tank is just being set up.

[ChloroPhil]

Debbie,

I'm just that good...ROFLOL!

JDS,

Good call. I've never seen a discus with sunburn, but I think 3x 250w MH bulbs will do it.

[stygian7]

[quote author=JDS link=board=7;threadid=12886;start=0#133692 date=1064758159]
You know you're probably right. I don't know what I'm thinking. In reality I have to get new bulbs anyways because I know that 10000k probably won't work well for plants.
[/quote]

Biotypical is right about 10K working well. All plants have chlorophyll a; some have other secondary photoabsorbtion pigments, but chor. a is the major player in absorbtion. A 10K spectrum peaks at just over 400nm, almost exactly where chor. a absorbtion peaks. Furthermore, the part of the spectrum that you are losing (the reds), happens to be the part of the spectrum that water itself absorbs. Most aquariums aren't deep enough to really absorb much of the red, but for this reason, many aquatic plants are inefficient at absorbing the red part of the spectrum.

Besides that, your fish will look a lot better under the 10K than under a 5.5-6.5K light.