Anticipated Swimmer Load on a Pool

[saml]

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.

Thanks

 

[duraleigh]

I have no formula but I've had 30 kids in my pool with no huge FC change.

In your 22k pool, I think boosting to 10-12ppm would sound just about right. I'll bet you stay above 6ppm all day.

 

[chem geek]

Sorry this is so late -- I only just noticed this particular thread. It seems that a rough guide for chlorine usage due to ammonia and urea from sweat and urine is for spas somewhere in the neighborhood of 7 ppm per person-hour in 350 gallons. In a swimming pool, it's around half that amount unless the exercise is vigorous (continuous swimming). So you can scale that accordingly where larger water volume would have correspondingly lower FC usage since the total chlorine quantity would be constant.

In 22,000 gallons, this translates to 1.1 ppm FC for every 10 person-hours for continuous swimming and half that or less for simple wading. Remember that these numbers are rough guidelines and that the loss from sunlight will likely be the biggest factor.

Richard