No, the DP1 is a module itself along with being a dosing pump. It also has two switch inputs.
Yes, you can use any switch input on the system. Since mine is in the garage I use a switch input on a module that is at the sump. I use the auto top off DP1 switch input for low and full levels on the DI water container. I use those to turn on and off my RODI unit to fill the DI tank.So if I wanted to use DP1 as a auto top off pump, could I hook a float switch directly to the input?