I have a 400 gal spa with an ozonator. The spa is reasonably balanced with a pH of 7.6, TA=55, CH=155, CYA of 80. I increased the CYA to that level because of my chlorine problem, but it didn't seem to make a difference. The problem is that I need to put in 8 times the amount of 12% liquid chlorine called for to raise the Cl to the desired level. For example, to raise the level from 0 to 5.5, Pool Math shows that I would need 2.3 oz of liquid chlorine. In fact, the spa required 16 oz. In addition, the chlorine level decays extremely rapidly, returning to 0 in a day or two despite the high CYA level. Bound chlorine level is low at less than 0.5. I have not changed the spa water in quite some time (over a year) because I'm trying to not waste water; I don't know if this could somehow contribute to the problem. If anyone has ideas about why this is occurring, I'd really appreciate your thoughts!