Here's the deal: Pool is clear, but for the last couple of weeks, chlorine numbers have been in the .5 - 1. range for FCL and .9 - 1.6 TCL. My CYA was at 30 so I added 6# to raise it to approx. 60PPM, it's at 38 today. Yesterday, I added 2.5 gals of 12.5% shock and 3# of powdered shock since the pool was cloudy and the numbers were so low. During the night the SWG worked for 8 hours (at 70% output) adding more chlorine to the pool. This morning the FCL was.06 and TCL was 1.2. What happened to my chlorine? I expected to be in the teens still. Pool pump runs 24/7 for a turnover of approx. 21k per 24 hours.
Fiberglass 20k, SWG and sand filter.
I'm stumped. I was told it's chlorine lock and advised to use 6# of an oxidizing shock to break this situation. Any suggestions?