There’s a reason that there is a whole genre of wisdom called “old wives tales”. Now that’s a politically incorrect term these days but it’s used here to illustrate a point about chlorine pools. These are bits of wisdom that become part of our behavior even if there is little evidence to support it.
For example, I was always told as a child never to put my coat on the bed of any house when we were visiting. We’d go to a party and everyone else was throwing their coats on the bed but not us. We hung ours up and were adamant about it.
Years later, I asked why we always did that and my aged mother told me that her mother (my grandmother) had an experience where she believed she caught lice from putting her coat on a bed at a party. This became our standard down through generations even though I’ve never met anyone else with that same experience. It’s just the way I was raised.
So when I started to question the wisdom of swimming in highly chlorinated (bleach) pools, I got the same kind of response which was, it’s the way it’s always been done and nothing else works. Although the sensation I had of dry skin, red eyes and bleach smell every time I went in a pool was pretty horrible, everyone else seemed to accept it although nobody seemed to like it.
So how did this become the conventional wisdom? The answer comes from the same reasoning as most unexamined behaviors. It was something that took on credibility as time went on even if new evidence had come to light that made that belief obsolete. This is the case today with residential pools treated with high levels of chlorine.
Residential pool owners are told every day to adhere to the same guidelines as heavily used public pools, even though most residential pools are 95% empty for 95% of the time! This approach of using a shotgun to kill a gnat is no longer necessary and only continues because there is a lack of vision within the water treatment business and, of course, there’s lots of money being made selling all this stuff every month.
Chlorine, in addition to being very unpleasant to contact, is a marginal bactericide, a lousy algaecide, and a terrible virucide
In fact, a case could be made that many of the typical problems we have in residential pools are caused by the use of chlorine itself, which is slow acting and is rendered useless unless the alkalinity of the water is constantly monitored and maintained. For example, at a pH of 8, which is not uncommon in salt pools, the active oxidizer content in chlorine is only 3% available. Which is why you need higher chlorine levels in salt pools, as much as 4-5 parts per million, in order to maintain any kind of effective sanitizer level. The World Health Organization (WHO), recommends that public pools be shut down when chlorine levels exceed 5 ppm. The whole story unravels when examined closely.
Stabilized chlorine, in addition to being very unpleasant to contact, is a marginal bactericide, a lousy algaecide, and a terrible virucide. If chlorine was so effective in pools, there would be no need for algaecides, clarifiers, shocks, balancers, buffers and phosphate removers.
Chlorine clearly needs a lot of help to do its job and has been surpassed by more effective, non-toxic oxidizers that have been used for decades.