Hey, that 50 should be able do it. What is the temp under the lamp? A good way to help retain heat is put some aluminum foil over around half the top. And ya even though its the cool end that's a little cold. Or you will have to play with your placement of your domes till it gets abit warmer on that end. I would put the probe under the lamp though or if you want to know what the middle is all the time to get another thermometer so you have 2. You want to really watch how hot its getting in the warm end because you don't want to dry him out.