Since I like gadgets, I decided to finally set one up. I bought this small unit custom built from Aquatic Systems by Scott McLeod. He's a standup guy and very helpful. There seems to be 2 major controls: effluent, and solenoid. I have two pH probes connected to my AC 3 (well one, the neptune lab grade is coming in the mail). One will be in a high flow area of the sump, and the other will be inside the reactor. I'm thinking for my controller to turn on the effluent if my pH rises above 8.3, since it only goes that high at night for a few hours (weirdly enough), and off again when it gets down to 8.28. This will basically make pH swing a bit less, but also be a good time to use the Ca / ALK when I can bring the pH down a bit. But then how do I control how much Ca / ALK goes in? Does this all have to do with a fine balance between the bubble count and the effluent rate? What's a good base line I should start at?