Thanks for the welcome!
I'm awaiting delivery of my test kit so have been using pool store's water analysis. The CYA has been consistently over 100, as high as 138, though last test (3/22), after I drained a foot of water, was down to 100. Most recent analysis includes the following:
FC 3
TC 3
pH 7.6
TA (adjusted [whatever that means]) 71
CH 451
CYA 100
Saturation Index (not sure what this means, either) 0.4
Water is slowly draining again through garden hose, and I'm hoping for the best. Perhaps I should drain 2 feet this time.