As Vgorst said you NEED a thermostat in order to maintain temps, you can't keep turning your lights on/of manually. So you need to but a dimming thermostat and some more digital thermometers, set it up so to create the required thermogradient. Take a look here
on how to setup a thermostat and also on what your temps should be and where you should be reading them. I hate to break it to your but you have done it the wrong way around, you are supposed to research and then purchase, not purchase then research so best get researching, read as much as you can, at least you've come here, this is a great place to start.