I think it was the range of temperatures. In the day 80-82 and towards night lower than 60. I now have a thermometer and watch periodically during the day to be sure. I had gotten rid of the sickly and kept as many as were healthy and I seem to be back on track now! YES!!! I really do enjoy watching them grow as I do having them for my daughter's pets. Certain ones she's not even allowed to take and she gets attached herself. I have decided to keep the hamster looking brown and white male away from everyone else since he seems to be doing so well now by himself. Not sure if I will ever be able to breed him but I've grown attached. The really HUGE cleaning did help!!! But now I will really really watch my temps even if its freezing in my house! That doesn't mean anything. My toes could be icicles and they could be roasting.