Yeah, I agree with Kurt... your bigger problem is keeping the fire belly in with the Whites. He's slowly poisoning the whites considering how much he's probably sitting in the water dish. As far as the heat goes...go to a reptile shop and ask the sales person for a heat lamp that you can use when your temps get too cold. It would be best to also get a thermostat that will turn it off it gets too hot in the enclosure. You don't really want to cover the whole top because they are going to need ventilation. 78 degrees is a good temp to keep them at. Your definately going to want to do something about the housing situation. For the time being at least have separate water dishes. The whites dish would have to be off the ground somewhere maybe up on a study ledge or something. Remember frogs absorb the water through their skin and if they're using the same water dish the whites will be the first to show signs of trouble. Change the water in their enclosure everyday.