With a CYA of 80, take the chlorine on up to 25ppm. You need to continue to keep the chlorine high until you can go from sundown one day to within two hours of sunrise the next morning without losing more than 1ppm of chlorine, you don't have more than 0.5ppm of CC and your pool is clear. Brush the pool daily after you add the bleach. Try and test as often as you can as you are doing and each time, take the chlorine back up to 25.

If your pH drops any, add a little Borax.

Hope this helps.