Everything I've read here says pH will rise when using a SWCG. However, while setting up and testing a spread sheet I've developed to determine approximate ozs of Chlorine gas produced for various running time and production %s for my SWG, and plugging the resulting values into Pool Math's "Effects of adding chemicals", The results show increases in FC as expected but DECREASES in pH. As the amount of Chlorine gas produced goes increases so is the decrease of pH getting higher. Having run my SWG for about a month now, I haven't seen any increase in pH and have actually seen a net decrease. Not much, but still a decrease.