Thanks for the responses everyone (even if a few were slightly perverted..:wink: ).
I was wondering where others are at with this as I've been seeing about a 3 degree swing since I added another halide to my tank. Might be time for a sump fan...
As I said mine hasn't moved but I did forget to mention I don't have a canopy and just the stupid fluorence that came with the tank. I'll have T5's & MH and a canopy in a couple of weeks.
I have been able to keep my temp. stable at 80 and my (old) house can cool down quite a bit when the outside temps dip below zero. My tank is only 6 months old, so I'll have to keep an eye on it this summer (no A/C).