OK, I'll give that a try. As long as I can limit the temp swing to 1 deg I'd be happy. I figured that a 15% water change would increase the temp by 15% of the difference between the two water temps. So to limit the swing to 1 deg I would need to get temp of my new water down to around 85 deg which should be possible, especially if I do it early morning. I'll freeze some jugs of water and drop them in the trash can tonite and see what the temp is in the morning.