I do have a K2006. Pool is 16x32, 17,500 gallons, vinyl liner. Appearance of water is crystal clear.

My CYA tests are not working, I've tried to dilute with 1/2 pool and 1/2 tap to get a reading, but may have to go 1/3s. My numbers as of Monday were:
FC 4
pH 7
TA 80
CYA - Guessing 200, was 165 per store test, and I cannot get a reading, and I don't trust them.

Since then I've drained 2' out of the pool, replenished. At this point I really need to try to get an accurate CYA reading so I know how much to FC to add (guessing per the best guess chart I need FC 8-15). I'm afraid CYA will still be high though. I can't effectively drain the pool any lower as I'm on a well. I will try another CYA reading soon.

I bought this house/pool last year and continued what the owner was using, stabilized tabs and trichlor which I'm learning is not my friend given it's been used and likely accumulating over the 10 years this pool has been here.

Any other advice welcomed, I'm new to the forum and apologies for not giving the pool water condition/other pertinent information in advance.