d3rryc, I ran my ca reactor w/your method for almost ten years. It's a pain to monitor it, but it does work. I know everyone says you need a ph controller, but I never invested in one either. If you monitor your calcium demand, get your effluent and bubble rates dialed in correctly, then things should be pretty stable. I'd recommend looking for a new regulator/solonoid if the rubber band idea doesn't work. Marine depot had a basic model that was under $100. Best of luck.