Quote Originally Posted by sabres07 View Post
Added info: I re-tested and FC was down to 18.5 which means I lost 15 ppm in less than 24 hours with no swimmers usimg pool. Water is crystal clear and I have held pool over shock level for 9 days. I need help!
Did you lose CYA over the winter? As I understand it, CYA can be eaten by certain bacteria over the winter and the resulting byproducts (sorry, I forget exactly what they are) create a huge CL demand in the spring. I've experienced this several times, although for seem reason it did not happen this past winter. If this is the case you will just have to keep at it with CL until all the byproducts are gone.

Hopefully someone more knowledgeable will chime in as well.