Quote Originally Posted by aylad View Post
Your CYA got as high as it is from the use of stabilized chlorine like trichlor--with trichlor, for ever 10 ppm of chlorine it adds, it also adds about 6 ppm of CYA, so over a 2 year period it can get quite high.The only way to lower it is through water waste (splashout, frequent filter backwashes, partial drains, etc). It will come down, eventually, if you do not use any more stabilized chlorine, but it will be very, very, very slowly. You can do several partial drain/refills to help it along without hurting your liner too much, but if you completely drain the pool, the liner will float and will not be able to be refilled, in most cases, which is why Pooldoc stated that #1 above wouldn't be recommended. However, you could drain some of the water--a foot or two at a time, and refill that, and shouldn't hurt anything.
Ok so I would drain the pool until there is 3 or 4 inches of water in the shallow end refill the pool and repeat this 3 or so times and then check the CYA level again. When it has normalized which is between 10 and 50 PPM how would I avoid this problem in the future? A friend helping me this spring had me do 4 separate shocks with 4 full containers about Gatorade sized of granulated Trichlor to kill my algae and that is when I saw the stabilizer level go way up on my test strips. Is using Stabilized chlorine at all a bad idea? How does one use calcium hypochlorite appropriately?