I started putting ice in Wiggles's enclosure and he's loving it. His cool side ambient has been a bit high lately (82F). I don't have central air-conditioning, and it's been hot and humid lately. So, I reached into my recycling bin, grabbed a couple 32oz water bottles, filled and froze them. I use one during the day and switch to the other at night. I put it in the lower tub. Cold air sinks and there is less air flow there, so that's where I reasoned the ice would be more effective. It's only resulted in a 5F drop, but Wiggles hasn't left the tub since I started, so I'm thinking he likes it.