Recently I was at a brand new pool. It had been filled the day before I serviced it. The water was trucked in from an underground lake. The water chemistry was pretty good. pH, TA, CH, CYA, and salt levels were all properly adjusted. I was there to do the first vacuuming so the pool looked perfect for the customer when they got home. I found that the chemistry was all in good shape with the exception of the chlorine levels. Both FC and TC were reading 0. The salt system was set at 50%. I turned the salt system up to 70% and shocked the pool. My thinking was that since it is the beginning of august and we have been experiencing weather in the high 80s for the past month, and the forcast shows the same for weeks to come, I needed to get chlorine in the pool quickly before algae took over.
My boss, on the other hand, didn't agree. He said I shouldn't have shocked it. I should have let the salt system bring up the chlorine on its own.
So I'm wondering if anybody has any information on how rapidly algae can grow in a pool with no chlorine. Is there a way to calculate how much algae will grow, or maybe find the tipping point where there is enough algae that it will begin to consume chlorine faster than it can be produced? Is there a way to calculate chlorine demand based on how long algae is allowed to grow?