I think I figured out where the extra heat is cumming from. I have a 150watt grow light in my living-room for my house plants, well the end of the tank gets direct light from the grow light, foolish me I had no idea it would raise my temps that much. I must be getting a greenhouse effect at that end of the tank. might need to rearrange my space and take the HPS 150 into account, almost the time of year i can turn it off for the summer anyway. Thanks for getting me thinking.