MH on a 46g bowfront

[rmhuntley]

I've got a 46g bowfront and recently got 2 250w MH setups, the tank is 36" wide and 17" tall. Would it be overkill if I used both halides on this setup?

 

[RegalFlush17]

I think that it would definitely be overkill, not to mention the heat that 2 250 MH would contribute to the system. With just one of the MH you can keep any type of livestock that you want depending on how high above the tank is. If you mount the MH with 6" of the surface of the water, you will have enough light to support any livestock.

Goodluck

 

[rmhuntley]

Kinda what I figured, but it never hurts to get a second opinion

 

[clayswim]

You should have one lamp per 24" of tank length, so two lamps would be fine. 250W is quite a lot for a 17" deep tank though; 175W would be preferable. If you're keeping corals or clams that require intense light I don't see where this would be a problem.

If you mount the MH with 6" of the surface of the water, you will have enough light to support any livestock.

Metal halide lamps can actually be placed much further from the surface without any negative effects; and really should be to eliminate heat. For practical purposes you should place them within 18" of the surface.

Clayton

 

[RegalFlush17]

The amount of light penetration, I thought, was directly related the height the light is above the surface of the water.

 

[rmhuntley]

I was actually thinking about mounting the bulbs 12" above the water in a fan cooled hood w. open back. I got both Halides in a raffle, so I only had a choice of 250w. I realize there will be some heat issues, but will deal w/ that when I run across it. I plan on running the lights for only 3-4 hours a day while its hot, then increasing as the temp outside cools down. I also plan on using a clip on fan in the sump area .

 

[jlehigh]

What do you plan on keeping in the tank? You answer will guide the correct decision.

No doubt 250W MH is allot of light but there are also plenty of animals that like the light. You can also use higher Kelvin bulbs which have lower PAR output if you like the colors the blue spetrum brings out.

 

[Llarian]

I'll second the "What are you keeping" question. When I was designing an acropora and tridacnid tank, (50G 36"x18"x18"), I was concerned that 250W wouldn't be enough without overdriving the lamp. (I was planning on 20K lamps however)

-Dylan

 

[rmhuntley]

I'm planning on having a mix of SPS, LPS and softies. I could do 1 250w MH and have low loght areas on the ends.

 

[clayswim]

The amount of light penetration, I thought, was directly related the height the light is above the surface of the water.

Light is absorbed by both water and air, but water absorbs at a much faster rate. Metal halide lamps have enough intensity to travel through air with great efficiency, as opposed to fluorescent lamps. While there is some weakening, it's a very low amount in the first two feet of air. It's the reason halides will also travel through several feet of water before losing their useful power; while fluorescent tubes will only work in the first 18" or so.

Clayton

 

[Hoopsguru]

I also have the same tank sitting empty right now and have some halide parts I could use on it. My tank has the black plastic center brace and not sure if your tank has the same rmhuntley. Would this create a shadow in the very center of the tank if using only one MH (175w) or would its impact be insignificant?

 

[jlehigh]

I also have the same tank sitting empty right now and have some halide parts I could use on it. My tank has the black plastic center brace and not sure if your tank has the same rmhuntley. Would this create a shadow in the very center of the tank if using only one MH (175w) or would its impact be insignificant?

I hope this helps you both out. Way back when I had 1 175W MH over the center of my 46gal bow. It definately created a shadow so I retrofitted it with a clear acrylic brace instead of the solid plastic brace it cam with. I'll attach the best pic I hav of that lil retro job, but essentially all I did was cut a strip of acrylic to fit. Place it over the current brace. Pre-drill through both the new brace and the old about 1.5-2" from the edge of the tank. Screw in some nylon screws/bolts through both the new and old brace. Then I used a hacksaw and cut the old brace out right from beneath the new. I did this with a full tank. An empty tank is a bit easier.

Hope that helps.

 

[Hoopsguru]

Excellent....I have seen the methods of removing the entire brace, but I like the "anchoring" so to speak off the new brace into the old.

 

[Angelscrx]

I was going to metion that the 250 MH might melt that plastic brace but the acrylic brace replacement would solve that!

You could also go to the LFS and see if they would trade for the 175w ballast too if you are too worried about too much light!