hmmmm, i'm not sure what that could be...... i can give you some of my opinions and you see if it feels like it may be something you might try. i personally don't like my water at 80 degrees.... wait is your room 80 or water 80? water should be between 72-75 degrees is what i think is best and room temp is fine if between 70-80 during the day.

OH! make sure that NO light is getting into your water basin! if there is ANY light getting in there, you can get an algae buildup and that can mess with your PH very easily.