Split off of this topic. This discussion diverged from the original topic, so was moved here. JasonLion
As i've posted before, i lose CYA all the time. Not as fast as chulaman, but its considerable. i've lost, as far as I can tell, close to 30 ppm this season. I've NEVER had my chlorine go even close to zero, nor have I ever measured any ammonia, nor have i had any combined chlorines that would indicate its presence. There is something, somewhere, somehow that causes the CYA to breakdown besides the conventional wisdom here. I've stopped worrying about it and just bought and added more. (although I would like to know where it goes).