GTakacs's guess and your hypothesis is right on, it's the high chlorine. Forget the strips as they are less accurate in will be hinderd even more by the high chlorine. My experience with the Aquachem though is that you are better off letting the chlorine come down before testing for anything else. The other problem is the limit at which it can test the chlorine and it does not test Free Chlorine or Combined Chlorine, just Total Chlorine (FC+CC=TC) which WILL lead to problems. My advice, buy a better test kit that will test for both. You want what's called a DPD based chlorine test kit. This forums sister site poolsolutions.com has the best in my opinion (Ps234 which test for everything) but you can also get one by Taylor (not sure of the number). The $90 bucks seams high at first but it and a constant eye will pay for itself the first season. Ben is behind in shipping so it will be a while before you get it so the sooner you order the better.

Dave