Using well water and historic problems with mustard algea

[karl_ga]

New forum user. Doughboy above ground 28 round 18000 gallons 225# sand filter with 1 hp pump. Just south of Atlanta.

Believe my historic issues are caused by stabilizer buildup during the season using Bioguard and others 3 inch chlorine tabs.
Ran between 0.5 to 0.9 ppm copper and still kept appearing last couple years. And leaves from pear and pecan trees!

Used 4 bags of Bioguard cal hypo burn out at end of season a week for two weeks to clear it up.

Starting with some leftover 3 inch tabs and have added six bags of the cal hypo over last two weeks.
Then added 5 boxes 20 mule team borax and 5 lbs of soda ash and ordered a k2006C kit just now.

Q. Add some of the bisufate from BioGuard that I have to reduce ph below 8 and add some more borax?

2Q. What other testing capability do I need? Borate strips? Copper testing? Or will K2006C be enough?
Plan to use bleach and/or 3 inch trichlor non-stabilized tablets if they can be found locally.

Thanks in advance