Help another temp question

[Aquattro]

Just a few thoughts here. I think the fan is a great move, although your evaporation will increase. I'd also set the heater to come on at 80F, just to reduce the swing. Last summer, my tank went from 80 to 89 every single day for 2 1/2 months, and the only thing stressed was me. My corals grew, my fish were fine (acting normal) and I saw no indication of a problem. I did have lots of circulation to O2 in the water, but overall, it wasn't a problem. If your tank inhabitants are healthy, a swing of 4 degrees is nothing.