Nanobubbles vs Salt Chlorinators: A Salt Pool Is Still a Chlorine Pool

In short

A salt water chlorinator removes the chemical delivery, not the chemical. Salt goes into the pool, an electrolysis cell converts a small part of it into hypochlorous acid, the disinfectant does its work, and the chemistry largely reverts to salt so the cycle repeats. You stop storing drums. You do not stop swimming in chlorinated water.

A nanobubble system does something structurally different: it oxidises organic load and pathogens in the circulation loop using oxygen or ozone, and forms no chlorine at all. Where a residual is still required by regulation, it is kept deliberately and at a much lower level.

• Chloramines still form in a saltwater pool, because free chlorine is still present. The smell, the stinging eyes and the irritation come from chloramines, not from the drum the chlorine arrived in.
• Salt genuinely solves chemical storage, handling and delivery, and it holds a very stable low residual with less manual dosing.
• Salt introduces an electrolysis cell that scales and wears out, and a mildly corrosive water chemistry that some materials do not like.
• If the goal is to remove chlorine from the building, read what chlorine-free actually means before you buy anything.

What a salt system actually does

Salt is dissolved in the pool water to a low concentration — typically a few grams per litre, well under seawater and low enough that most bathers describe the water as soft rather than salty. Pool water then passes through an electrolysis cell, where a current across coated titanium plates splits the dissolved sodium chloride and produces hypochlorous acid in the flow.

That hypochlorous acid is the disinfectant. It is the identical molecule you get from hypochlorite solution, granules or tablets. It disinfects the same way, it reacts with sweat and urine the same way, and it forms the same chloramines and disinfection by-products. Once it has reacted, most of the chloride returns to the water and is available for the cell to convert again, which is why salt consumption is low and top-ups are occasional.

This is why the question “chlorine vs saltwater pool systems” is framed wrongly almost everywhere it is asked. Both are chlorine systems. The real differences are logistics, dosing stability, water feel, equipment wear and cost — not the chemistry in the basin.

A useful test when reading any supplier’s page: if a saltwater pool were genuinely chlorine-free, it would not need a free-chlorine reading. It does, and the health authority will ask for it.

How nanobubbles work

Nanobubbles are gas-filled bubbles under roughly 200 nanometres across. Buoyancy barely acts at that scale, so instead of rising and bursting they stay suspended for days, carrying a negative surface charge and an enormous combined gas-to-water surface area.

The NanoSWIM Pool System generates them continuously in the circulation loop after filtration, charged with oxygen or ozone. Gas dissolves far more completely than through coarse injection, bubble collapse drives oxidation that breaks down pathogens and organic load, and the surface charge lifts fine particles and biofilm off walls and pipework so the filter can remove them.

The consequence for this comparison is simple. There is no chlorine in the process, so there are no chloramines to form, no chlorine smell, and no salt in the water to attack stone, grouting or metal fixings.

Honest limit: nanobubble treatment produces no measurable chemical residual of its own. In a public pool that still needs one, you keep a small chlorine level — see Nanobubbles vs chlorine for how that trade actually works.

Dimension	Salt chlorinator	NanoSWIM nanobubbles
Disinfection mechanism	Electrolysis of dissolved salt into hypochlorous acid — chlorine, generated on site	Oxidation from bubble collapse plus dissolved oxygen or ozone
Is it chlorine-free?	No. The water contains free chlorine at all times	Yes, or greatly reduced where a residual is required
Residual in the basin	Yes — stable and easy to hold	None of its own; a small chlorine residual is retained where the regulation asks for it
By-products	Chloramines and trihalomethanes form as in any chlorinated pool	No chloramines formed; ozone reverts to oxygen
Chlorine smell	Present, because combined chlorine still forms	None, because no chlorine is dosed
Operating cost	Low: salt top-ups and electricity for the cell, plus cell replacement	Steady modest energy draw; chemical spend falls sharply
Maintenance and consumables	Cell cleaning and eventual replacement; salinity and pH monitoring	Scheduled generator servicing; no cell and no chemical drums
Effect on materials	Salt is mildly corrosive to some stone, grouting, ladders and untreated metal	No added salinity; lower chloramine load on the building and ventilation
Water feel	Soft and pleasant — a genuine and frequently cited advantage	Soft, with no chemical residue for skin to react to
Best fit	Private and hotel pools that want no chemical storage and a stable residual	Facilities where air quality, sensitive bathers and chemical spend carry real cost

Costs vary with pool volume, water hardness, run hours, salinity set point and local electricity prices. Ask for figures against your own pool rather than a generic table.

Corrosion and equipment wear

This is the most under-discussed part of owning a salt water pool system, and it deserves a clear-eyed look before installation rather than after.

• Salinity is low but permanent. At a few grams per litre the water is far from seawater, but the chloride is present continuously, and chloride is what drives pitting corrosion in susceptible metals.
• Vulnerable materials. Untreated or low-grade stainless fixings, some natural stone copings, mortar and grouting, and certain heat-exchanger materials all react poorly to a long-term saline environment. Specify materials for a saline pool from the start; retrofitting salt into a pool built for fresh water is where problems usually appear.
• Splash and evaporation zones. Damage often shows first outside the water, on handrails, anchor points, deck fixings and ductwork, where salt concentrates as water evaporates.
• pH drift. Electrolysis tends to push pH upward, so acid dosing is usually still part of the routine. A salt pool is not a maintenance-free pool.
• Chloramines remain a building problem. Because free chlorine is still present, an indoor saltwater pool has the same combined chlorine and the same corrosive load on ventilation plant as a conventionally dosed one.

Cell life and replacement cost

The salt cell is the consumable in a salt system, and it is the number most buyers never ask about until it fails.

The plates carry a catalytic coating that is gradually consumed in normal operation, so output falls over the cell’s life. Manufacturers quote a rated life in operating hours; the honest questions to ask a supplier are what that rating is for your model, what a replacement cell costs today, and whether the price includes fitting. Get both numbers in writing before you sign.

Hard water shortens cell life by scaling the plates, so calcium hardness management and periodic acid cleaning are part of ownership. Self-cleaning cells that reverse polarity reduce the manual work but do not eliminate the wear.

Comparing honestly means comparing consumables. A salt system replaces chemical drums with a cell; a nanobubble system replaces both with scheduled servicing. Put five years of each on the same page before deciding.

When salt is still the right choice

There are pools where a salt chlorinator is plainly the better purchase, and pretending otherwise would not survive a site visit.

• You need a residual and you need it cheaply. If the regulation, the insurer or the bather profile requires measurable free chlorine everywhere in the basin at all times, a salt cell delivers it with less capital cost than any equipment-based alternative.
• Chemical handling is the problem you are solving. If the real pain is storing, transporting and dosing drums — particularly on a site with limited plant-room space or untrained staff — salt fixes precisely that, and it fixes it well.
• Dosing stability matters more than by-products. A salt cell produces chlorine continuously and steadily, which is far easier to hold at a set point than manual or batch dosing. For an outdoor pool with variable load, that stability is worth a great deal.
• Budget is the binding constraint. A salt chlorinator is a modest purchase. If capital is unavailable, it is a real improvement over drum dosing and it is available now.
• Bathers like the water. The soft feel of a lightly saline pool is a genuine benefit, widely appreciated, and not something a nanobubble system replicates in the same way.
• Your pool is outdoors. Most of the strongest arguments against chlorine are about indoor air quality. Outdoors, chloramines disperse, and the case for changing technology is weaker.

If that list describes your facility, buy the salt system. We would rather be useful than persuasive.

Who should choose what

A short routing guide for the three situations we see most often.

• Choose salt if you want to stop handling chemicals, need a stable residual, run mainly outdoors, and are not trying to eliminate chlorine from the water.
• Choose nanobubbles if the chlorine itself is the problem: an indoor hall with air-quality complaints, bathers with eczema or asthma, a hotel or spa where the water is part of the guest experience, or a chemical bill you want to cut permanently.
• Choose both, in effect, if you are a public facility: nanobubble treatment carrying the disinfection load, a much smaller chlorine residual for compliance, and no drums on site. That combination is common and it is a legitimate answer.
• Choose neither yet if turnover rate, filtration or pH control are your actual problem. New equipment does not rescue a plant that cannot circulate the water properly.

The practical retrofit detail — flow rate, plant-room space, how the loop is arranged — is on pool water treatment. If you are also weighing UV or ozone, see Nanobubbles vs UV and Nanobubbles vs ozone.