Mirror
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.
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