How to protect acrylic from MH light?

[petedoc]

Any thoughts on how to protect the cross brace on my acrylic 270 gal tank from the MH light over the center of the top? The tank has three 250 watt MH lights in Luminarc reflectors. The bulb is 12" above the top of the tank.

[Hop]

Possibly with another piece of acrylic cut the same as the top of your tank spaced a few millimeters above the tank. This would allow a bit of cooling and if cracking/crazing began to occur, it would be on the disposable piece, rather than the tank.

[petedoc]

Hop good idea, I think I have some thin scrap acrylic around that should work just fine. Thought about placing a reflective material on the brace, but that would create a 6" wide shadow in the middle of the tank.

[Hop]

I can't claim credit as Melev mentioned it to me about two years ago, but since I never added a MH right above a brace, I never applied it:)

[spleen93]

Actually, I'm not sure you'll need anything if the bulb is 12 inches away. I've got 2 250 watt MHs over a 50 gallon acrylic (admittedly they're over the openings and not over the brace) but only about 6 inches away from the water in a canopy. I've got fans blowing on them while they're going and I too was worried about potential heat damage from the bulbs to the acrylic bracing but I threw a thermometer probe on the bracing and left the lights on for about 10 hours and it never got above 90 degrees. If mine didn't get above 90 degrees 4-5 inches away (since the water is another inch down), don't think your acrylic will be affected 12 inches away as long as you have fans going.

FWIW and definitely YMMV.

Spleen