I use the Reefkeeper Lite for control of the pump (regular Tom's Auqalifter attacjed to some rigid tubing stuck in a 5 gallon petfood container (because it's square and tall and easier to hide than a 5 gallon bucket). The Reefkeeper has a pH probe and it sends the signal to the controller. The pump comes on when pH falls and turns off when pH minimum is reached.
I evaporate more than I am adding kalk so I also have an ATO with just RO water independently from the kalk drip