I just ordered my TF-100 Test Kit so I'm not sure what my readings are yet, but I've been getting my water tested at a pool store. I was told my PH and Chlorine levels are fine, and that my Conditioner was over a 100 so everything was good to go. My water is clear so I trusted that everything was ok so I kept adding Trichlor tablets via floater not knowing what exactly they were doing to my CYA levels. Now that I know better I've stopped using the dreaded tablets and switched to Liquid Chlorine from the pool store (planning on switching to BBB ASAP). So I had my water tested again at the pool store, and I got the same results PH and Chlorine levels are good and condition is over 100. So I asked shouldn't I do at least a partial drain to bring down my CYA level? Instead of getting a yes response I was told that since it gets so hot and sunny here in Southern California they recommend keeping Conditioner levels above 100. But everything I've read here suggests I should bring my CYA level down. I know the previous owner of the house used Trichlor tablets, and I've been using them for about 6 months now so I can only imagine how high the CYA levels are right now. At this point should I start a partial drain? If so what's the best way to start draining? I have what I think is about a 25,000 Gal. in ground paster pool with a cartridge filter. I've read about people backwashing and draining/vaccumming to waste, Etc. to do partial drains, but since I have a cartridge filter I'm not sure how to drain water. I have a drain at the bottom of the deep end of the pool and one skimmer drain, but the control panel only has an option to drain the spa? Any help would be appreciated. Thanks in advance.