You will lose some through water splashout and water replacement which will dilute it some but this won't be significant. Some people, me included, typically lose all their cya over the winter and have to readd each spring. But, I would doubt that with a cya reading of 100 that it would be likely to drop to 0. That being said, unless you do a partial drain, you will most likely continue to have a cya reading of 100. Some people decide to just live with it and maintain the higher chlorine levels and do just fine. It is just a matter of preference. At any rate, no more trichlor tabs in your pool or your cya level will just continue to rise. Hope this helps. Let us know what you decide to do.