So I bought a low-bay MH fixture (it's 2feet by 2 feet). Went to LFS and dropped the cash on a nice 400w 20000K bulb.

So I should have taken into account how exactly I'm going to hang the 14lb fixture.

Of course after buying chain and what not, i do now have a stud to hang the light from.

How bad of an idea is it to just sit on top of the tank over top top the piece of glass in the middle of the tank?

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I dont see it being to bad just take into account a couple of things.

1st The bulbs gets really hot and will heat up the water also make sure it does not melt the brace going accross the tank and the plastic rim on it.

2nd The fixture will get hot and might be a pain to move it when you need to get in the tank.

The plastic rim on the middle brace is what i'm concerned about. Is there any way you can think of to get this light up off the tank a bit without having a stud in the cieling to attach it too. The light is to small to put on brackets. it fits bassiacly in the middle the tank. it doesn't reach both sides.

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what size tank is this going over. I know it sounds like a pointless question but it will give me an idea as to what you are working with. It can be done for I have rigged up many hailides over my tanks. just check my build thread

Don't do it! I've personally had a 250w MH placed 2" above a 3/8' glass cross brace overheat the glass and cause it to break. These lights put out tremendous heat. Get a suspension kit and hang it the way it should be.

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Doc

Dr Hank's 200 gallon Reef Tank
http://www.aquariumforum.com/f46/drhanks-tank-3440.html

I would have to agree with Doc if the bulb is going to be directly over the brace it will dry rot the brace or melt it all together. Even if you were to hang it the brace will still overheat and block alot of light in the process. If you are going to have it over open water then you can do it. Thats why I asked the size of the tank.

its 48 inches long, 26 inches wide,

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Then you most likely have 1 center brace in the middle. I would not use that light. But sell it and get 2 250 hailides it will be better with less heat.

That is not an option. However i do have 2 of the MH fixtures. Can i use 250 watt in a 400 watt fixture?

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If it is a mougal base bulb (single end) then yes but you will have to get new ballasts. I am not sure about HQI bulbs. But if you have 2 then you can use both 400 watters 1 on each side and it should not effect the center brace. Just use some fans to blow the heat away from the brace. But you will have to get a hanging kit like doc said. The are not to expencive.

the hanging kit is not the issue, the issue is what do i attach it too? there is no stud in the ceiling.

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well with out seeing your set up the best I could say right now is to run 2 2X4 beams off the back of the stand and hang them off of that. Not the best looking way to go about it. But if you use your imagination I am sure you can figure it out or show me a few pics and I can think of something that would look good and work good at the same time. Also dont use paint on the wood 400 watt hailides will burn the paint just a heads up there I tried it and crashed and burned. Wood is fine just no paint.

heres the tank

The start of a another reef 150gal

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Firts off nice tank. We can do this. Does your fixtures look like mine. Keep in mind I made the wood box for the reflector

If so just mount the fixtures to a 2X4 and the figure out a way to mount the 2X4 in the canopy. The way I did it was I installed 2 short boards from thr front to back of my canopy on each side. Then mounted the lights to a 2X4 that was cut to size so it sat on the boards like this

That way I dont have to unscrew anything to remove the lights. Just unplug them and remove. If you look closely at the last pic you can see the boards they rest on on the left hand side it is the same on the right. I will try to get better pics when I get home tonight. Also with the depth of your tank you will want the 400 instead of the 250 like I said earlier.

ok now I looked more closely that is not a canopy I was looking at. Do you have a pic of the fixtures you got. Me I always go canopy so it makes things alot easier and they are cheap to make yourself and I did mine in about a weekend.

So do you have your light board screwed into the canopy or sitting on the 2x4 that's screwed into the canopy?

PS: I don't have a canopy however as you said they aren't difficult to make.

PSS: Yes my fixtures look exactly like yours however the fixture also houses the ballasts.

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IMO there are a few things I would worry about. Putting glass over the tank would cut down your gas exchange. Then you are heating your water up by putting 400watts right on top of it. You can't use a 250watt bulb in a 400watt ballast you will burn the bulb up. I have a 400's over a 48" tank and at 8" about the tank I still worry about heat. I have to use 4 computer fans and have another house fan blowing on the ballast. You may make out better if you sell that light or trade it for someting else. Or you can find a way to rig a hanging kit.

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If It Is To Be It's Up To Me!!!
http://www.aquariumforum.com/vbgoogl...216796875&zoom

thanks for the horrible news :(

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My light board is sitting on 2X4. I would Remove the ballast from those fixtures With the heat from the bulbs it will shorten the life of the ballast. Also dont use the glass tops for the same reason trouble93 stated. It cuts down on gas exchange and lowers light. As far as heat you will have to watch that. But I have seen lots of people with 400 watts over tank. Get about 6'' clip on fans. They work way better than computer fans. (Bigger and blow harder) They do make more noise though.

where should i mount the ballasts?

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