Let me start by saying that temp control for fermentation is on top of the to-do list because I fully expect it to rectify my issues. But in the meantime, I have an IPA that is just chugging along slow and steady. It's 4 gallons of a pretty standard IPA that has been in the carboy for 16 days and I'm still seeing active fermentation. There is still some foam/krausen on top, the air lock is bubbling every 7 seconds or so, and I'm still at least 10 points from my typical finishing gravity, but it does continue to go down, slowly. I don't have any glaring indication of a stuck fermentation or any other big issues but this experience is different from what I've had so far so I'm just looking for some insight. I have identified a couple of variables that could be behind the change in fermentation behavior. First: The yeast is White Labs Cali ale yeast and It's on the 4th generation. I usually make a starter a couple of days ahead of time and split the yeast. I use one to pitch and put one in the fridge for next time. How many times can I propagate this way before the yeast starts losing vitality? Second: The average termp in my basement is about 63 degrees for 16-18 hours/day but the thermostat is set for 62 overnight and I'm not entirely sure how many degrees the basement drops overnight. Being a basement, the temp doesn't generally swing very far, very fast but I suspect the temp could drop down to 60 or slightly below. Could a mild and regular temp change like this contribute to a slow fermentation?