I was using faulty test strips & ran my CYA way up to 99 PPM. Then I found your forum, had Leslie Pool try to sell me 45 Lbs of water hardener for my vinyl pool at $76 and now I'm trying to figure out your way. I ordered the test kit from the site and I'm attempting to dump half of my pool water to replace it and get better sanitizing from my bleach as well as have the ability to shock if necessary with a lower CYA. Is my thinking sound? Should I shoot for 50 PPM with around 12 hours + of direct sunlight on the water per day?