Just changed to BBB, chlorine has gone to zero twice in last 5 days. What am I doing wrong? Each time I re-chlorinated according to the pool calculator. I 've had this pool for 12 years, and only other time this happened, was when the phosphates were really high. (I live under an oak forest). But tested it for phosphates today, and result was zero.
Very frustrated! help! Gunite finish. on pool.