I am new to this site. Since last 6 months I have been operating my pool by using Trichlor 3" tablets for FAC and Calcium Hypochlorite 56% for shock. Since supply water is good, parameters like TA (80 ppm), Calcium Hardness (260 ppm), pH (7.6) etc. have been good, needing no chemical addition. Main control issues were FAC (maintained by frequent shock doses), Algae formation and rise in DE filter pressure from 25 psi start to 35 psi (max) in 3 months.
Recently FAC became nil and on analysis CYA was 100 ppm (checked at vendor shop). Replaced around 5500 gal of water out of total 17500 gal (though recommended to be double that but limited by disposal issues) and switched from Trichlor to 10% liquid chlorine bleach (added 2 gal few days back and another half gal today) to limit algae and filter pressure rise. This has helped only to a limited extent. Filter pressure has also risen to 35 psi in less than a month and needs an immediate back-wash.
What is the way forward. Usage of pool is limited to two of us. Not rechecked CYA again, but will replacing another 6000 gal or so help? Can 10% bleach be used both for control and shock. Should I then discontinue Trichlor tabs? Any other additives?
Appreciate any suggestions on the above.