The idea is for an alternative to either chlorinated or salt-water systems for hot-tub or swimming pool water sterilization systems.

The question is whether ponds of water in series can be kept relatively bacteria free by alternating them between carbonated and fresh water states so that conditions remain neither aerobic nor anaerobic long enough for initial bacterial growth while destroying whatever bacteria do happen to grow before each subsequent switch?

Picture a series of hot-tubs water-falling from one to the next, decreasing in temperature at each level but which then steam back to the uppermost tub at the end of the cycle.
The condensed steam is pure water and needs no chemical purifier, so initially the uppermost tub is aerobic and before long will begin to grow algae. If the water for that tub were then carbonated any aerobic bacteria should die and anaerobic life forms will begin to grow.
Meanwhile the lower tub now becomes anaerobic as the upper tub switches back to fresh water, while the third tub... etc. etc...

Would such a system keep bathing pools as free of harmful bacteria as conventional purification methods?

Sorry to ask but I'm having a hard time figuring out the search words I'd need to find the info.
-- 2 fries shy of a happy meal, Jul 14 2019

It may not be the aerobic/anaerobic change as much as a change in pH that's the critical factor; [MB] or [bs0] will know.

However, the use of ozonolysis in swimming pools is fairly common. Highly aggressive oxidation kills bugs while being less irritant than chlorine.

A controlled shift between different chemistries will certainly militate against the development of any one type of organism.
-- 8th of 7, Jul 14 2019


There is a solid logic here. You can certainly inhibit bacterial growth by adjusting the conditions, at least for a while. If you switch the conditions often enough you can get on top of any microbes that are specialists. This is done when you clean things in labs, you alternate between a bleach-based cleaner, to an acidic cleaner etc. to prevent adaptation.

The problem is, you're rotating which pool is in use, how often is there space for a couple of extra pools for rotation? I think what should be appreciated, is what something like chlorine is very good at, its very oxidizing and very reactive. It doesn't just stop bacteria growing, it reacts and destroys the vast majority of the molecules they're made of. Better than that, most aerobic microbes are looking to make a living by taking reduced carbon sources, oils and other assorted human slime, and extracting energy by oxidizing them with oxygen. Chlorine is aggressive enough that those molecules are oxidized very rapidly, completely eliminating their food source. This goes on in the whole system, in all the nooks and crannies and pipework.

A saturated CO2 solution would remove the dissolved O2, and drop the pH. Aerobic microbes wouldn't be able to grow, but they could easily wait until the situation changes.
-- bs0u0155, Jul 14 2019


The answer is obviously to bathe in liquid chlorine rather than water. It can be liquefied at typical ambient temperatures simply by compression, but there may be cost considerations.
-- 8th of 7, Jul 14 2019


You could dissolve a little DNP in the water. It would make any bug with a membrane potential (all of them) into an energy wasting machine. They'd consume all the organics, then each other and eventually themselves. No chlorine needed.
-- bs0u0155, Jul 14 2019


Yes, but the downside is that DNP in water (a) looks like wee and (b) stains skin pretty impressively.
-- MaxwellBuchanan, Jul 14 2019


It would make the real wee less noticable...
-- bs0u0155, Jul 14 2019


Not in the know, apparently. (Per usual...sadly.)
-- blissmiss, Jul 15 2019


//There is a scary video out there showing bacteria adapting//

Hence why in lab situations, cleaning solutions are rotated. You rotate between acid, bleach (oxidizing) and alkali based cleaners. Bacteria can eventually adapt to almost anything, but not everything. There are acidophile bacteria, but not ones that also tolerate extreme alkali and extreme oxidizing conditions.
-- bs0u0155, Jul 16 2019


I do not use fluoride mouth rinse, but it seems plausible that a harmless antibacterial at a mouth rinse might cyclically complement a harmlessly antibacterial toothpaste. I have heard both cheese prevents tooth decay so perhaps an emulsified oil at the toothpase and some less yucky tasting ingredient from listerine could complement each other cyclically. Then again, perhaps there is zero correlation between the number of bacteria in a mouth, the recovery time of S. mutans tooth plaque, and actual cavities. It might be a novel, potentially effective breath freshener though. Another possibility is a morning toothpaste and an evening mouth rinse, each with very different ways of terminating plaque and breath scent bacteria.
-- beanangel, Jul 16 2019


The series of tubs, especially if anyone is bathing in them, will have turbulence, and therefore the two solutions (aerobic and anaerobic, or other complementary pairs) will end up getting mixed with each other as they move down the line.

// I have heard both cheese prevents tooth decay //

Oh, I haven't tried that kind yet. There's a cheese shop on the way home—I might stop there and see if they have some. (Or did you mean the Japanese band?)
-- notexactly, Jul 22 2019



random, halfbakery