my two cents.......
i have never had a heater in my tank, i know our weather in good old England is a lot different to yours over there, but it regularly fluctuates between 70 and 85 degrees. the halides pay a big part in this obviously. its never really caused concern and hasn't seemed to affect any livestock in my reef. I've never had to raise the temperature in the tank but have had to chill it. i have found the easiest way to chill, (without a chiller) is to freeze up some bottles of water to float in the sump. with not a lot of skill needed you can work out how much frozen water it will take to drop the required amount of degrees. if you don't have a sump, you just use smaller bottles/containers but more of them, and drop em in your tank!
may sound a bit mad, but its a proven, safe and most importantly, cheap way of dropping degrees!

sap???? lmao..that's funny

i will have a redneck chiller in a few months, although the basement is a constant 57 degrees year round so I should be able to benifeit from the neatural temp a little

one thought though blue...........if you are haveing huge swings in temp, try cycleing your lights - on for 2 hours off for an hour back on again......it's easier to control 2-3 degrees rather than 10-15............like when you turn off the AC all day while your at work and the house is 105 degrees when you get home.......people don't realize you will burn less energy keeping the house at 68 degrees all day rather than cooling it off from 100 to 68 all at once ...............just a thought, check with the others on cycleing the lights, don't wanna make the fish and corals crazy from the lights going on and off all the time

Boss

yup

hehehehehehe