I've used this method for the past few summers with no problems but I am trying to help a friend. They've used chlorine for years and this year are having problems with a crystal clear pool testing at zero fc. I tested a sample with the tf-100. Their cya is 60. What could be the problem, they've added lots of shock, chlorine granules?
Having never had to SLAM, I'm not sure if that's what they need to do or not. Any help would be appreciated.
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