Mirror

[DJ88]

Victor,
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Well...couldn't you put it on both ? Both water and reflector ? I don't have HIDs, but I have heard that blow air at both water and lamps helps reduce the water from heating up too much. Just a suggueston...

Here are some quotes from elsewhere in the thread that hopefully will answer a few things in your question.

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It is a heat sink. But removing that heat from it isn't nearly as efficient as putting a fan that is hitting the waters surface. I have tried.

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Just an FYI, using fans to cool the air temperature in your hood (eg. blowing fans at your reflector or lamp) as opposed to using fans blowing onto the water's surface to effectively control temp is not one of the best ideas. Cooling the air temperature around the lamp will cause a shift in the spectrum emitted by the lamp. Everyone hates 5500K lamps because they're too yellow, so why would you blow air at your reflector or 6500K lamp therefore causing the color temperature to decrease if you could avoid this arrangement?

These were found due to peoples experience with MH lighting. HTH

[Rainman58]

I used mirrored plexiglass in my canopy which contains 3 X 150 watt MH, 2 X 110 watt fluorescents and 4 X 40 watt fluorescents and have had no discolouration or melting at all. My canopy is 14" deep with the fluorescents mounted approximently 1" from the plexiglas and the MH mounted 5" away from the plexiglass. I`m also running two 4" Icecap fans (one at each end of the canopy) for cooling with 2 1/2" holes drilled in the lid for ventilation. This seems to work pretty good and i`ve never had a problem with my water temp rising above 80 degree`s.