What kind of reactor are you using? With the sulfur-based reactors, many people connect an aqualifter pump to the inlet and have the controller turn it on when the ORP value drops below ~ -170. I'm going to attempt similar control via a DP1 pump to regulate the drip rate and increase it when the ORP value drops. Implementation is in the works - I just set up my reactor this weekend and I'm waiting for it to cycle. I'll update status after I get it up and functional.This is good information. I just set up a nitrate reduction reactor and have read on other threads that there is a way to control the amount of carbon dosing using the ORP probe.