Just an FYI on heat...
I currently run a 250w MH 6" above the water with no chiller or sump. I also have 3 20w actincs for supplementation (I wish I had VHO for coloring but I'm upgrading to a 90g soon anyway).
My canopy has an open back and I run 2-4" computer fans that blow across the water's surface during the time the MH bulb is on. I have my heater set for 78F. So, in the summer I usually run about 80 - 82 max and in the winter right at 78 - 80. These aren't daily fluxes just temps throughout the yr. I usually only run one fan in the winter. And yes I do have AC and the thermostat in the summer is usually set at 78 during the day.
Anyone running dual 250w over a 58G or similar size? I'm thinking of doing this for a 50G. I decided against a 400w due to the center brace on the AGA 50 (I didn't want to have to shield the brace and create a shadow in the middle of the tank).
I have a 58 Gal Oceanic and use a CustomSeaLife PC fixture with 4 96W bulbs. I leave the light resting on the tank and have not used a chiller. There's a total of around 4 inches of open water around the fixture which allows evaporative cooling. Occasionally I've used a fan in the summer but have not been as concerned about higher temps after reading the Great Temperature Debate (somewhere on this site). Since I have 4 bulbs I can mix up various combinations of color temperatures as I see fit. This setup requires topping up about a gallon a day of fresh water.