Hi sobrien. If your CYA is at 60 ppm, then a FC level of 2 ppm is too low to properly disinfect your pool water. If the FC level went to 0, it is being consumed by biologicals, algae and/ or bacteria. How does your water look, is it clear? You need to shock (super chlorinate) your pool water until your combined chlorine levels are less than 0.5 ppm. Then bring and keep your FC at levels appropriate for your CYA level. You can find these charts in watermom's and pooldoc's signatures.

Tom