The middle school Sunday School class is coming to swim. Is there a way to "get ahead" of a forthcoming step increase in swimmer load to ensure FC does dip below the mininal value? Is there a calculation or rule of thumb to anticipate what the chlorine usage will be per person and I presume it would have to be for a given time. I guess that would make it chlorine use per swimmer-hour. Or is the overall use is such that all a person needs to do is test when they're done and get the level back up? Also, I would think I might be limited to 10ppm FC so as not to make it a discomfort on anyone. If it matters, the CYA is somewhere around 80 which corresponds to about 6 FC minimal.