For my 7 month-old pool, my PB used tri-chlor tabs for the first 30 days prior to converting to the SWG. For approximately 10 tri-chlor tabs in 22k gallons added 6-7 months ago, what would be my current approximate level of CYA?

According to the poolcalculator.com at the bottom ... One 7 oz tri-chlor puck will add 1.3 ppm CYA in a 22000 gallon pool.

So the 10 pucks have added about 13 ppm of CYA.

You really should get a good test kit so you can know what the levels are.

On an indoor pool you should be ok, but splashout and carryout could have affected it a little bit. The heat of the water will have minutely affected it too.

Thanks for the replies. I have a Taylor K-2006 FAS-DPD kit that I use regularly, but the CYA testing level only goes down to 30, and with no visible cloudiness my CYA level is below that 30ppm cutoff. Is there a CYA test kit that goes below 30ppm?

Not really. The test in the TF-100 goes down to 20ppm so is SLIGHTLY better but keep in mind the accuracy on that test is somewhere around plus or minus 10ppm.

If your goal is 20ppm for an indoor pool, I would calculate that dosage using the pool calculator and trust your math.