Potential Halide

[miketurn]

Hi,
Currently on my 90 gal reef tank I have two 48 inch coralife power compact lights so I have 4 x 55 watt actinic bulbs and 4 x 65 watt 10000k bulbs.

I have the opportunity to get a 400w metal halide with ballast and a spare brand new bulb for 50 bucks.

My plan is to keep one of the coralife lights for actinics and a bit of the 10,000k daylight from the PC's and replace the other coralife with the metal halide.

My tank has a large peice of glass bracing the middle and i've hread recently that you can't put a halide over the glass like that or the temperature gradient will cause it to crack.
So I'm jsut wondering what to do.. can i put the halide up but run some good fans (which I have lying around) into it to minimize the heat?
or maybe put the halide on one side or something? I feel i can't pass up this good of a bargain but I don't want to be stupid either.
Oh and currently I hvae no SPS..but the plans are to get some if I have the halide. thanks!

[scumchug]

1 - Cut out the center brace.
2 - Throw it in the bush.
3 - Eurobrace the tank.
4 - Enjoy

This is rather difficult if the tank is full. :)

On a more serious note. Its pretty tough. Do you really want to chance cracking the brace and your box spilling its guts onto your floor? I have melted the plastic braces. Believe it or not, its a much easier fix than the glass brace.

Now is the perfect time for the 180 gal you have always wanted..

[miketurn]

Hmmm..well this seems like a bit of a conundrum
. The tank is fully stocked and i dont trust myself to do any glass work.
Does putting the light on one side or fairly high up with fans help at all?

[scumchug]

Both ideas would work, but they are less than ideal for the obvious reasons.

I have cracked glass tops with MH lights, but never had to deal with a center brace. I know thicker glass transfers heat more evenly. That is evident when drilling. More care has to be taken when drilling thin glass. The heat transfers faster and more unevenly than thicker glass resulting in breakage.

I have a glass panel on the bottom of my light fixture. It's only 5mm I fully expected it to break from the heat of 1400 watts of light less than 12" away. It's kept clean and dry, and has air forced through the fixture. Not that it cools the glass necessarily, but helps distribute the heat evenly.

One MH over a 4' tank won't really do it anyway. I would get another and run them on each side. IMO each light will only cover a 2'X2' area effectively. Even if you ran a 250 on the other side to balance it out a little.

[mollyb]

I used to run old style metal halides over my centre braced FW tank. There was one to each side of the brace, and I did not have a problem. In fact, I never even thought there might be a problem, if I did, I may not have done it. I did have a centre brace give way once (I don't think it was light/heat related), the silicone actually gave up and one side of the brace came unglued, of course the tank was full. Probably didn't notice it for a day or more, and then I was freaked out, the glass can bow a couple inches over 6 feet!

After dropping the water level 1/3 (with a siphon, not because it leaked), I shored it up with 2x4 braced from across the room, wedged against the wall and used a 2x6 as a makeshift 'beam'. Then I cleaned the brace and the tank, and resiliconed the brace, held it in place with masking tape while the silicone set, and left the external bracing for 24 hours. The tank is still in use, this was about 9 years ago. Not recommended for fun though....

As an afterthought, if the brace was low enough in the tank, you might be able to discharge water from the filter over the top of the brace, and let it waterfall into the tank, might dissipate heat, but on thinking about it, it may only dissipate heat in some areas, due to inconsistent water run off, and cause more of a thermal shock differential. Bad idea....sorry

If the MH bulb was to the side, you could stock that side with the animals that required it, and leave the other side for the animals you have now. Might be nice to see the difference, I understand you can actually bleach out your rock/corals with a MH light, so it might not be all rosey...

[miketurn]

Hmm..
ok well I think I'll still go for it. I mean 50 bucks seems like a deal I can't pass.

I'll just make sure I put it on one side so that I can have some SPS or a clam on that side..and I'll just load the thing with fans.

I don't really want to start cutting in my tank or anything..i'd rather just wait till I bought a new one or something in a couple years or till i save up enough to buy a full MH system instead of ones with just a reflector like this one