Most of the PS chlorine starts at 12% but does lower with heat and time. I say mine is 10% just because I would rather go over than under.
Kim
Thanks Kim for the info. I don't buy mine from the pool store, so I wasn't sure how theirs ran, but that's the only other thing I could think of that could be the issue on him getting the higher than expected levels when he adds what PM says to add. I think most people do just go ahead, and plug in the 10% for that very reason, don't they? I also agree that it's better to be over than under, especially when fighting algae, so just trying to keep him from being too much over, if he doesn't have to be.
Have a wonderful day, and I hope classes are going well.