Use the BBB method and pool is over 40 years. Vinyl lined -inground- DE filter -23000 gals .Readings yesterday showed PH at 7.3 Chlorine at 2.5 and Alk at 133 and CYA at 69. Over the years I have fought staining and have used abcorbic acid to put into suspension and then a culator to remove with success . This year not having any luck as added (2) quarts of the blue stuff and the culator and it comes back in 2 days . I thought it was the Kem Tek 60 algaecide but they said it does not contain copper. Im lost what to try next ? Do have a Raypack heater and thinking maybe it is the source but based on my readings dont understand why that would be .HELP