Quote Originally Posted by matthew64 View Post
It was 3 bottles of the walmart type (http://www.walmart.com/ip/HTH-Spa-No...blets/17043664) over the course of 2 weeks.
No wonder. You ended up with a false chlorine reading. If you have any left, use them in the toilet tank -- they're not bad for that. (And, it will get rid of them safely!)

Read the Best Guess chart; with a CYA>100, 20 ppm will be the level to hold till we've determined what your actual CYA level is. By the way, it's perfectly safe for swimming -- after you've cleaned up the 'algae' (which is actually bacteria!).