Retested an hr later, up to 7ppm. So seems to be correct that I can get 6ppm per gallon of bleach. I added another half gallon, will retest this evening. I searched some older posts on here regarding hard water, high cya pools here in az. Saw some recommendations for pool chlor company, who apparently use cl gas once a week? And possibly a calcium chelator? Wondering how many people have had to go to this and if it is an option. I'd rather do it myself overall, but time becomes an issue at some point.