I have been having the same problem. It is two weeks now, and my pool is using extreme amounts of bleach. I thought it was getting better, then today it dropped 12ppms I think it may be all of the pollen and caterpillas falling into the water. I keep getting no cc and the water is clear, but I don't really want to drop the chlorine down low until it is holding overnight. I have been trying to keep it at 15, but may try boosting it up to 20 again for a time to see if that is what it needs. My cya is only at 30. I will keep you informed