i use a 250 watt hps in a 3'x2'x4'h and temps were around 100-110 degrees F. added cooltube brought it down to 100. added a 6" inline duct booster for exhaust with passive intake holes, brought temps down to room temperature or slightly above. i would go with t5's, cfls could heat up spmething quick if it was really short, i wish my box was more than 4', it was such a pain in the ass to get cooled down.