Hello,

Luke the semi-professional pool guy here. As regards to Jack's Magic, I do use their products regularly for stain removal. The purple stuff is correct for salt water pools. Blue stuff for chlorine pools. The stuff does work. But once you are on the product, you have to continue using it to keep the stains away. Most of my clients spend about $300-$400 for stain removal than $40 or so a month keeping the stain away.

Jack's Magic is the best in stain removal technologies. I love them, expensive, but good.

Luke

ps... jack's stain products will lower the ph, but not purple or blue stuff.