My first post. I've learned a lot from this superb site. I had a dark green pool when I opened it. I already put 21# of shock powder and 5 gal. of liquid shock in my pool. This work great last year. The pool is now light green. Taylor K2006 FAS-DPD measurements now are FC 2.0, CC 3.0, PH between 7.0 & 7.2, TA 50, CH 150, CYA 0. The Pool Math calculator says to be careful if the CYA is truly zero. I have four 3" tabs in a floating chlorinator; have been using 3" tabs for about 20 years (but will use bleach from now on). I'd appreciate any advice before I add anything or buy more liquid bleach to shock it. Thanks, Doug