You have to buy the vortec module, it allows the apex to switch through the driver settings on the vortec... Basically you can program nutrient mode at "x-time" then reefcrest from "x-x" then lagoon mode, night mode etc etc.... I think it's called a wxm module iirc????
The WXM is what you need on the Apex side. You also have to have the wireless version of the Vortechs for them to communicate. You can upgrade to the wireless version if you don't already have them.