i dont have a sump using a red sea max 34. with 3 hids two 10k at 55 watts and one 8k at 35 watt. temp stay at 78 to 80 with lights running at 8 hrs. when i run the t5s water temp gets real hot. so just running the hids now. the system is a closed unit.

http://www.maast.org/showthread.php?...-Max-34-Gallon