Have a SWG 26,000 USG pool here in Katy (West Houston) Texas.

Just went to local Pool Warehouse on Mason and got water tested again an CYA is still low at 30 ppm and that's after adding 2 4.5 lb jugs !

So bought another jug for USD16.99+tax and will re-test after 2 weeks. You can also buy via web companies. I've looked and never seen in WalMart or Home Depot.