I have a 18k in ground pool with high cya. I plan on draining and going swg so the cya shouldn't be a problem but I am curious about that bio active stuff. My cya is starting out between 120 and 140. I'm using a hth liquid test kit. I know it's not a Taylor but it's what I have. I plan on starting the bio active tomorrow or the next day depending on my chlorine levels. I am just curious about this stuff. I know there is a lot of people that say it doesn't work but there are also alot of people that say it does. I will keep you updated either way