So question then...how long does it take the tabs to build up
unacceptable CYA levels? I currently have a pool with probably
only trace amounts of CYA. I bought a tub of the 3inch tabs before I
found this site and read up on the BBB method.

I think my pool is around 22000 gallons, plaster IG. We switched from
Bacquacil to Chlorine about 3 weeks ago. I just finished cleaning out the algae /leaves and haven't managed to get the chlorine to my proper levels yet. I started on liquid bleach (6%) and haven't used tabs at all yet.

Mariza