T5 are getting too hot

[Tab64]

I have noticed since switching out my PC for T5 my tank was hotter. Well over the Christmas weekend, no A/C was on, the tank got up to 84-86 degrees this will never survive a FL summer. It fried a few corals. They turned black in one day. The T5 are mounted under a canopy running on an ice cap ballast. This is generating more heat than the old PC I had for years. I would like to keep the canopy but can remove the flip top. The canopy is wood, matches the stand and hides on the hang-on things which would be visible, tank is in living room so total removal is not an opion.

The tank is a 4', 55 gallon. I am thinking of removing the flip top which would create an opening of 4'X8" to allow more heat the escape. This would loose 2 of the t5, I would still have 2, one mounted at the front and one on the back of the canopy, angled toward the center of tank. Could I get away with a small MH maybe 150 watt that would be 12"X8". This would allow a few feet of open canopy for the heat to get out. It seems to me the extra open space will work better than those tiny cooling fans.

 

[Fishieness]

yeah, the t5s run a heck of a lot hotter when overdriven on the ice cap VHO ballasts.
how high is the hood? you may not be able to put a MH in there, but you probalby put keep on of the flip tops open and put a pendant over it. although you will probably still ahve some heating issues. id instal some fans in your canopy.

PS: what corals turned black at 84-86 degrees?!! that seems a little harsh. maybe your thermometer is running low because i have had my tank get up to 88 before. i had some anthillia die and some sps turned a bit brown, but nothing really turned BLACK. then again, it was only like that for a few hours. (same deal.. forgot to turn the AC on)

 

[Tab64]

The canopy is only 5" high so mounting MH will not work. I can not use pendants the ceiling is vaulted and is 14' at that point. I was thinking of placing the MH fixture onto the opening after removing the flip top but do not know if the small 150 is enough or is the fixture would be too hot to sit on the wood canopy.

The first to go was the xenia and finger leather. Although the flower leather and toadstoll are fine. A few others look a bit iffy and may recover but the leather turned black overnight.