I'm running into the same issue I had last year and I figured its time to ask here
My cya appears to be out of control, and I have mustard algae that continues to grow and I fear thats thats the issue. Here are my current levels:
CYA is 100+
As far as I can tell everything is ok except the cya, which I believe is stopping the cholorine from working properly and allowing stuff to grow. I've cleaned up all my plumbing and it as no leaks and appears to be filtering very well. Water clarity is ok but hazy and with obvious growth at the bottom (less than 12-15 hours after vacumning). I'm also in an agrument with a family member who helps me on this and is not into chemistry but is positive its not the cya levels.
I've also attached pictures of the chlorine tabs and shock packets we are using.
A direction to head in would be appreciated (even if I have to dilute the water, and a plan to keep cya from rising again).