You need a ph probe input. You will need a SL1 or SL2 module a ph probe and a spare outlet. Depending on how many modules you are already running you may not be able to add any more. The lite is limited to 4 modules and the Itemp probe counts as one.
Why do you need a controller to run a reactor? They don't run on their own? Or do you run a reactor based on what your ph is doing? I don't have a calcium reactor and my ph swing from 8.2 at night to 8.0 during the day. Is this a large swing and would the calcium reactor make it worse?
You can add one more module, so yes, you can add the SL1 or SL2 needed to control the reactor.
If you didn't have an extra module available, you would need to get a separate pH controller, like the MI SMS122, but you could power everything off of your PC4 outlets if you had extras, but you could not control the CO2 reg , just power to the separate controller.
