I used up all the bleach I had on hand last night and was able to get the number up around 7 or 8 I'd guess (per chart you recommended).

At work now but will buy out all the bleach at Walmart this afternoon and get at it again. Is that unusual that after 9 jugs of bleach it only moved the ppm to 7 or 8?

Is mine a particularly challenging case?

Tx watermom, I'll report back tomorrow.