I'm interested in an electrical/mechanical failsafe for my dosing pumps, which are controlled a by Reef Angel controller and powered by a DC relay box. I have two dosing pumps, one pumps water through my kalk stirrer and the other runs my ATO. I had a situation the other day where my dosing pump that runs my stirrer came on for no reason. Luckily, I was nearby and knew it was not supposed to be running so I shut it off. I moved the pump to a different relay and changed my programming to accommodate, and It hasn’t happened since, but I want to add a “hard” failsafe. Also, I would like something I could insert between the DC relay box and each pump (e.g. I don't want to move the pumps to an AC relay box because both are about full). Each relay on the DC relay box runs 12VDC at 400 mA max. Is there something I could easily add to restrict the runtime on these two relays such that each pump could run for only so long, or is there maybe a better way to skin this cat?