First of all, thanks for making this such a great resource. Our salesman told us nothing about water chemistry when we bought our new PDC Spa a couple months ago. I've learned everything I know about water chemistry on this forum.
Here's my issue. After a totally failed first fill that resulted in foamy water after about three weeks. I started with a fresh fill a couple of weeks ago. Got TA and pH into acceptable ranges and begin using dichlor to sanitize to roughly 3ppm after each soak. I should point out our spa has an ozinator. This was going well until I learned about the bleach method and realized my CYA at that point was over 100. I drained the tub down some and added fresh water to get CYA ~80. Even though I know that's an elevated CYA level for the bleach method, I started using bleach instead of dichlor. That was going well too until I realized my CC levels were waaaaay out of acceptable range. I'm talking in the 10ppm range when tested on my Taylor 2006 kit.
I've tried adding MPS, leaving the cover open in sunlight, super chlorinating with 2.5 cups 6% bleach, and nothing has worked to get those CC levels down.
I have two questions: how do I get CC levels down and is it safe to use tub with levels that high? I'm hoping I don't have to drain and refill...
EDIT: I should have added that the water is clear, I don't have significant foaming, and I'm not smelling noticeable chloramines