Next week I'm going to build my 6 tub 41 qt rack to house BPs. I've already purchased everything but the thermostat. It'll be heated by 6 individual pieces of THG heat tape wired together for a total of about 150 watts. I was first going to buy another hydrofarm tstat but I decided I'm not in a terrible hurry and I can afford a Vivarium Electronics model. I like the low profile table top style and I've only heard good reviews on it. What I need to find out is what model is right for me. What is the difference between proportional(pulse), On/Off, and dimmer style. I was thinking the VE-200D model but I'm not sure. I will be breeding my ball pythons hopefully next fall. I don't yet know if I'll be dropping temps at night. Any help is appreciated. THX