not going to mention any names...cough robmcd, went to rescue a few geos from him the other day hehe (btw thanks for the geos bro) anyways his tank was like 90 degrees. apparently he just plugged in his heater the night before from being disconnected for the summer. His geos were fine so thats proof they can withstand 90 temp for at least 1 night hehe. I'm sure he brought the temp down. I'd think any temp higher he'd have geo soup