Hi, for a ten gallon tank the 40 should be ok. If its to hot you can buy a dimmer for like 8 bucks at Walmart and you can control it like that or if you have the extra money you can get a thermostat. Put the light to one side this way the frog has a warm and cool side. If he is in the water bowl for days on end this is not a good sign usually. But if you had the UTH on the bottom it may have been drying out the substrate so he is sitting in the water to keep hydrated, you want your substrate to be wet enough that clumps in your hand when you squeeze it but you don't want water pouring out of it. If this is not the case you may need to see a vet because as I mentioned usually when frogs sit in there dish for days on end it is a sign of illness most the time. Now that you have changed the heating I would take him out and see if he goes back in.