I try to stay within 79-81. I added a heater to keep the nocturnal temps up and then added a fan to the light timer to blow across the water. It works so, so depending on temperature, humidity, etc.
It's spring time in florida, so the temps oscillate violently from day to day, so I switch between heat, AC, and open windows on a daily basis.
I really need to buy a chiller/heater to keep the temp more stable, so so far, I have coughed up the $800 such a unit would cost.
btw, the ballast emit a lot of heat, so be sure to keep them away from the tank. I had my in the cabinet with the sump and my sump picked up a lot of heat. I moved them out of the cabinet and my temps fell a few degrees.