2 things... float 2 litre bottles filled with frozen water in your sump... or fill a cooler with ice and coil some airline tubing in it. then attach your air intake for your skimmer to it. then your skimmer will pull in the ice cold air and cool it down a bit.
Yeah what he said. If you want to drop it quick and your tap water is pretty clean, throw some cubes in there. Also watch the indicator on your heater to see when it turns on and off. Maybe try dropping your temp on that by 4 degrees and see if that fixes anything. Other then that, fans work good for me.
With water that hot though, you tend to have more water precipitation. Let me rephrase. If you need to top off your tank, and want to get your water down quick - add some ice cubes. I would lend you mine, but you dont live near me. Not my ice cubes, but my frozen bottles.
I added a 5" fan over the sump and turned on my air cond to 78 deg and with that my tank in the morning is 78.0 deg and with the light on all afternoon my temp gos up to 79.1 deg. I loose about 1 gallon of water a day, but it keeps my tank cool
Definitely recommend trying a fan first. I think you'll be VERY suprised what a difference it'll make.
If you STILL can't get the temp down, then try the bottled ice idea.
One note: Using the fan WILL increase evaporation (considerably). This is in fact, HOW it can do such a good job of keeping the temp a little lower. One thing to keep in mind though, you WILL need to top off more frequently than you've been doing. But a very quick and easy fix!