I cannot thank you enough for responding so quickly! I can't tell you what a relief it is to feel that I have real support out there. Truly...I'm moved to tears.

Watermom, you asked a few questions:
What type of pool is this and what is the volume? Outdoor (uncovered; in-ground, gunnite), ~30K gal.
What type of filter and what size pump do you have? The filter is a pleated, papery, upright, cylindrical cartridge (not sure if this is helpful, but I do know that the contractor said recently that he thought it was probably too small for the pool) - we clean it at least once/week; pump is 230 hp and ~15 amps.
What have you used in the past for your source of chlorine? I moved in 1 year ago and during that time have only ever used trichlor tablets and occasional liquid (unstabilized) chlorine.
Anything else you have added? Be specific --- not product names, but ingredients: The only thing other than what I've already mentioned is a couple months ago, we added a TA reducer, 93.2% sodium bisulfate.

I did go out today and purchase a Taylor CYA drop-test (to add to my K-2000 kit). It tested at 100 (at least that is when the black dot became just barely visible; the point at which I could not see it at all was 120 - I'm not sure which is the correct reading.

In case it helps: Today the pool is looking blue (no green tinge at all), but is still cloudy.

Thank you, again, for all your help!! I'll definitely check out those links.