Please forgive me but I am an amatuer and homeowner with a 20' x 40' in ground pool in the NY area. I've taken my water to be tested at a reliable pool store and for 10 years I have successfully kept the pool properly balanced. Since I have a heater this is watched very carefully. For the past two weeks I've been getting high free chlorine readings in the pool. All other readings are normal. I've tested at the store and myself. Following the store's recommendation I shut down the chlorinator down for a few days then ran at a very low level. They also had me dechlorinate with chemical treatment. None of that worked. After that I tried filling the pool, which was at a lower level water than usual, with hose water. I realize the tap water has chlorine but in the past this has dropped normal levels to low. It's also rained a bit. The water still reads high chlorine - more purple on AquaChek than the highest level. The funny thing is the water does not smell like chlorine. And we have never had high chlorine in ten years. We've always had normal or low chlorine (which was easily corrected with the pool store recommendations). I guess I'm looking for reasons why this is sustained so long. Is my neighbor dumping chlorine at night? I'm joking. I have great neighbors. But I can't figure it out and the pool store is scratching their heads. Any thoughts?