I am having issues with my Pentair intellichlor. The cell light keeps flashing green and it stops working. I had the intellichlor 20 and I upgraded to the intellichlor 40 thinking maybe I needed a bigger one. Now I just turned that on and it is flashing green to inspect the cell. I looked at the cell and it is clean inside. Also, my white fiberglass pool has a yellow stain in it. New to pools and not sure how to fix these issues