l have had to add cya twice in a month.Added 4 pounds a week ago and had about a 40 reading on the tube.This morning it showed no chlorine or cya.Checked stenner and it is delivering properly.Against my better judgement I took a water sample to the PS where I buy my Cya and they checked the cya and it was zero.They said I probably have TDS.They tested for it and it was 2100. They said I should drain about 6 to 8 inches of water and refill.Only had an inch of rain since I added cya.Does this sound like a good plan?