I have a saltwater pool, and I accidentally let my FC fall too low and now I have an algae problem. Even though my OCLT only lost 1ppm and my CC is 0.5 I have algae. My question is looking at the pool calculator, it says to raise it to 21ppm to shock, but looking at the chlorine/cya chart it says I need to be at a level of 30ppm to shock. Which one is correct if my CYA is 80?