Chlorine Level For Private Versus Public Pools

[Wobbly]

Our pool has a very light swimmer load of 3 family members for 1 hour per day. Would it be unsafe to maintain chlorine levels in our pool at lower concentrations than the national standards require, considering that these standards are applicable to public pools with heavier swimmers loads, and more diverse swimmer profiles?

[chem geek]

The standards for commercial/public pools allow not only for the higher bather loads but for person-to-person transmission which requires a much faster kill time than simply preventing uncontrolled bacterial growth. However, algae requires higher chlorine levels to prevent its growth so if you maintain a chlorine level sufficient to kill algae faster than it can grow, then you will be getting plenty of protection against pathogens. If you wanted to use a lower chlorine level, then you'd need to use a supplemental algaecide or phosphate remover, at extra cost.

For manually dosed pools, the minimum Free Chlorine (FC) level needed to prevent algae growth even in pools with high nutrient (phosphate, nitrate) levels is an FC that is at least 7.5% of the Cyanuric Acid (CYA) level. If you use a supplemental algaecide, then you could go with a lower 1-2 ppm FC with a higher CYA level of, say, 80 ppm which is a very low active chlorine concentration technically equivalent (in hypochlorous acid concentration) to around 0.01 to 0.02 ppm FC with no CYA.