Hi all - we just moved into a house with a 25,000 gallon pool that has a Hayward Aquarite SWG. I purchased a TF100 test kit and have been using it since we moved in last week. The initial FC level was measuring in the 15-16 range, so I assumed that the previous owners had shocked the pool before they left; after 2-3 days the level did not drop so I turned off the SWG. It took 4-5 days for the level to come down to 5 PPM, so I turned the SWG back on; last night the FC measured back at 15. The SWG is set at 70% and my filter (a Hayward DE) runs for 12 hours daily. Other info - CYA was low at 40 so I added 4 lbs to bring it up to 60; pH is at 7.5; TA 200; CH 250.
My question is this - is it really typical for SWG to increase the FC that quickly? Should I reduce the SWG to 40%, reduce the pump run time, or both?