Originally Posted by BadgerBrewer
As long as temps stay between 64 and 70, and if they flucuate quickly back and forth, you should be fine. Remember that there is 5-6 gallons of wort and the thermal mass is fairly large. The temp of the wort won't swing as quickly or as dramatically. It should onlt change a few degrees and be right in the middle.
Air temp in the house is fairly constant at 72. The change in the temp of the wort is what is swinging up and down. Water/ice bath to cool. As Ice melts temp rises back up.
The fermentation was rolling at 76, but has mellowed at lower temps.