Don't have the heart to subject any more Bettas to my winter-chilled house without heating their water, somehow. Last year, I purchased a 7.5w heater designed for the 1-gallon tank. Ah-ha! Someone finally addressed the needs of mini-tanks. My thrill was short-lived. The heater fried my Betta. Temperatures hovered around 90-degrees! So much for label guidelines. Almost lost hope in finding a solution. Any ideas from the community?