Thanks Ben.

The pool installer gave us the 20k gal figure (installed in March 2004). It might be a little bigger, but dosing based on the 20k figure gets me real close. The 22ft width figure is an average of the narrower deep end, 18.5ft, and the shallow end, 24ft I believe. The pool is shaped in what's called a "lazy L" (not a true L, kind of in between a straight rectangular shape an a true L). The shallow end is 3ft (actual water level) and the deep end 5.5ft (they called it a "non-diving pool). I can send you pics if you like.

One winter some years ago I lost all CYA and it took a lot of CL before it would hold. Well, it seemed like a lot but that was when I was operating by pool store rules; I earned here they had me adding too little CL at opening. It was sometime after that when I learned here that CYA could biodegrade and about appropriate CL levels.

7.2 pH is pretty normal for my pool when I first open it. In the past I just let it drift up as the SWCG ran (another lesson I learned several years ago after the first cell died prematurely; only use the SWCG to maintain CL levels, NOT to shock!). I've not noticed any problems in the past doing it this way. Given this is it ok to proceed without the borax (I don't have any borax on hand, just boric acid [I maintain 50-60ppm boric acid in the pool])?

So, I guess the answer to my question above is to shoot for normal shock levels? I'll add the bleach tonight (I bought 10 jugs (121oz) of 8.25% bleach to have on hand for opening) and see how much I lose overnight.