Metal Halide over an acrylic tank - what precautions?

[steviep]

I'm thinking of putting 2 MH 250 watt lights over an acrylic tank. The tank has the 2 cutout holes in the top like this:


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Obvoiusly I would center the ligths over the holes, but what other considerations are there - how far from the water should the lights be? Should I cover the openings in the tank with glass? Do I have to worry about the heat cracking the center brace on the tank?

Thanks.

SteveP

[steviep]

Obviously the diagram didn't work.

The tank has 2 rectangular cutouts with a center brace.

[fitzgerald_jay]

if you center them over the holes then you should be fine. depending on how vented your canopy is, that will consider how far to put the lamps form the water. if it is well vented, you could go 6" with surface. good luck!!

[Rockfish]

I have two rectangular cut outs over mine. I have two lights that are just off center of the cutouts and two over the center bracing just off center. I run a total of six fans (three each side) mounted three in a row. Two outside blow in and the middle blows out. This configuration is on both sides. Lights mounted 8-9" above acrylic. Seems to run OK with not alot of heat build up on top of the tank. Acrylic is 3/4" thick.

Steve

[percula99]

Check out John Rice's nightmare when he decided to increase his MH lighting over his acrylic tank. He learned valuable lessons which he passes on here. This isn't intended to scare you, rather help you out before something goes terribly wrong.

Good luck.

http://www.globaldialog.com/~jrice/oddity_page/break.htm

[Rockfish]

John Rice forgot to plug in his fans before going off to work..bummer...He also splashed cold water onto the heated acrylic to cool off...another bummer...tried to repair tank with water still in it....last bummer...Result three strikes: Catastophic failure of tank. I definitely heeded all his warnings when I built my hood. I hardwired my fans to the lights so that they both had to come on simultaneously when activated. I also use the rule of not going into the tank until MH lights have been off 1 hour in order for any heat to dissipate from the top of the tank, this minimizes any water splashing damage that could occur. Read and Learn.

[percula99]

Thanks for the refresh Rockfish, it had been a while since I read John's page.

[Rockfish]

It's so funny his name came up. Last night I was looking through a big binder of aquarium info i keep, and I came across about 50 pages of material I had downloaded from his site. Of which he had pictures and the trials and death of that tank. I had used alot of his priciples and warnings when doing my tank. Last I heard he was going to do a 1100g tank. i wonder if it ever came to reality?