The difference in CYA and Alk could well be because of the difference in reported volume, I don't know....

Like Evan said, now that you're starting to hold chlorine, I would shock it up to 20 just to kill off the rest of the CC, and see if that doesn't make a difference in the demand.

The next time you talk to your pool guy that said bleach (which is 6% sodium hypochlorite) would ruin your liner, ask him why liquid chlorine (10-12% sodium hypochlorite) won't? It's funny to watch them hem and haw around that. Bottom line is, they're the same thing, but bleach is half strength, and easier to deal with (and if you're from Louisiana, the key word is AVAILABLE!). Of course, if you splash it directly onto the liner while adding it, it will discolor in those spots, but if you're careful when adding it NOT to splash it on anything, once it gets into the water it breaks down into chlorine and salt water. Nothing there that will hurt your liner, if added in the right amounts.

Looks like you're on your way to easy poolkeeping!!!

Janet