CYA 230, replaced 1/2 of water...now 217???

[waterbear]

two observations.
Pool stores will tell you that high cya levels are not a problem so they can sell you all sorts of copper algecies and clarifeirs when your pool turns green and they don't want to lose the very lucarive profits they make on trichlor and dichlor!

Testing for CYA is not accurate at levels much over 80 ppm and the sample needs to be diluted and tested to get an accurate result. If you dilute a sample of your pool water with 3 parts distilled water and multiply the test results by 4 you will get a more accurate reading on your CYA level. (assuming your cya is above 200 ppm). Also, from what I have heard, cya CAN deposit on the pipes and in the filter when the levels are very high and it is possible that as the levels drop more is redissolving into your water!