Can I Use Salt As Sanitizer Instead of Chlorine?

[PoolDoc]

And maybe all of that probably falls outside the expected scope of a forum like this, but...

well, it shouldn't.

My forum; my choice. Discussion of gastritis and the etiology of duodenal ulcers is not really germane here. If you want to start a swimming pool forum, where such things are considered OT, be my guest!

[catfish]

My forum; my choice. Discussion of gastritis and the etiology of duodenal ulcers is not really germane here. If you want to start a swimming pool forum, where such things are considered OT, be my guest!

I'm not the one who brought up postmodernism.

[BigTallGuy]

I said it once and I'll say it again. There is no "FREE LUNCH" when it comes to swimming pool sanitation. You're gonna pay the price somewhere, somehow, but burning my skin is not a price I want to pay.

[chem geek]

It doesn't help to move the goalposts around, so to speak. We started out talking about ocean salinity levels, but yes if we are talking about extraordinary salt saturation levels nearly 10 times higher then sure that may kill pathogens, but as was pointed out by others above is impractical for many reasons.

If we want to have a rational discussion about chlorine alternatives, we can have that, but why waste time going down dead ends? There are already quite a lot of alternatives we can discuss unless we're just having a brainstorming session online.

I didn't mean to discount the very real risks of chlorinated disinfection by-products. High bather-load indoor pools that aren't exceptionally well managed can be pretty darn awful in short-term effects (largely from nitrogen trichloride) and may be at least somewhat harmful for long-term effects (from brominated THMs and other chemicals, mostly regarding cancer). However, when I look at this data, I can see that reducing the active chlorine level to the lowest amount that still gives reasonable disinfection rates while simultaneously providing methods for removing organic precursors (i.e. bather waste) to oxidize them before chlorine does seems the easiest path to take, at least initially. I believe small amounts of CYA (20 ppm for indoor pools, for example) can be used for this purpose to have, say, the equivalent of 0.2 ppm FC with no CYA.

As for true alternatives, we need something for bulk-water disinfection and right now it looks like the quarternary ammonium compounds might be a reasonable candidate (I already discussed the problems with copper/silver, though for just preventing uncontrolled bacterial growth they are OK if one can deal with their levels and pH to avoid staining issues). UV or ozone can still be used to handle Crypto. That still leaves general oxidation of bather waste for which there are a lot of alternatives (ozone doesn't oxidize urea well, especially if it's not chlorinated, while UV only affects some chemicals). In addition to some selective oxidizers, such as MPS, the use of boron-doped diamond electrodes to produce hydroxyl radicals may be a good approach and might be one of the few things that can break down urea (other than chlorine, which does so slowly though possibly aided by the UV in sunlight that produces...hydroxyl radicals), though that remains to be seen.

And then there's the DIN 19643 system used in some countries in Europe that focuses on coagulation/filtration for removal of organic precursors, though they use low levels of chlorine in the 0.3 to 0.6 ppm FC range without ozone or 0.2 to 0.5 ppm FC with ozone (with no CYA, however, so still generally higher than I'm proposing).

Now for residential pools where person-to-person transmission of disease is a risk many would be willing to take since odds are they might catch something through other contact means (such as you described), then the focus is more on preventing uncontrolled bacterial growth and oxidation of bather waste. The same sorts of alternatives as described above could be used, but using a subset of them since the bather load is much lower. Just keep in mind that the risk is higher (though as a personal choice, may be acceptable) and usually the costs will be higher as well, at least up-front. I'm just very leery given my discussions with users of such systems when they failed, but realistically a properly designed system may not have the same problems as those that were used (or used improperly).