I have a similar issue. I have only 65W pc
50/50 lights on a 37g FO
tank. The temp was at 80 or so (or so I recall) for the first several days...but now the temp is up to 82-84 and even shutting off the lights doesn't seem to help! Our house temp is only around 77, so it's not getting hot...
I can't figure out what is causing the temp to rise like this if it's not the light...I can't imagine it is the two power heads... unless perhaps my heater is haywire and it is going on even though I have yet to see the light go on at all.
I was looking into getting an IceCap 4" fan to blow air across the water, if I can't figure out what the deal is.