Maybe, but so far my tank only drops a few degrees at night. I think maybe its just cus i feed them in the evening, and so they begin to get more active after that at night. All of them are constantly "tasting" the water, just opening a little to get a taste... and then when they sense food in the water they fully open. Its really neat to watch. The mussels dont open much though, just a little to circulate water. They are actually kinda boring. hehe
I will post pictures soon
-Diana