What kind of heater do you have, Kristie? I've been looking online & the vast majority of submersible heaters are vertical & won't work because the water in my tank is only a few inches. I found a couple of small submersible ones on Amazon that look like they might work, but they have poor reviews, and also no thermostat controls, which would make me nervous--I don't want to have to check the water temp constantly. Anyone have any ideas?