That'st correct - it was 230 before I emptied half the pool and replaced the water. The pool store's CYA read 230 before water replacement and 217 after. Posters suggested that CYA readings become inaccurate when they get up to a certain point - so I dilluted the water with 3 parts distilled water and 1 part pool water, then tested it with the Taylor test kit and multiplied the new value (35) by 4 to get the CYA number. That number came to 140 - so I'm within Ben's 100-200 range for min 8ppm.

I just want to be able to swim this summer without spending too much $ on a full water replacement since I will be redoing the whole pool in the fall - so the chart hopefully lets me do that after lowering the CYA to 140.