I just built my canopy, only running PFO 13K's 175 watt bulbs 2 of those on a 55 gal i have a 4" fan from RADIO SHACK in each end drawing hot air out none blowing in bulbs are about 8"above water since these lights are new i'm only running them about 2hrs. right now but water temp don't seem to be going up anyone else have any sugestions or does this sound ok the only problem i have is keeping water in my sump it evaporates rather quickly