Salt does not attack the pool. It attacks everything metal in it.

What to look for

1. The wall, and what it is coated with. This is the decision that cannot be fixed later. Galvanized steel is zinc-coated against rust and is the baseline on most above-ground pools; resin-coated walls add a polymer layer on one or both faces. Salt water is mildly corrosive and it finds bare metal first. Our permanent pools roundup identifies which walls are resin-coated on both faces, which is the specification to want if salt is in the plan.

2. The pump flow your generator needs. Salt cells are rated on the water moving through them, not only on pool volume. The Intex unit here publishes a required pump flow range as well as a gallon rating, and getting that wrong is the most common reason a salt conversion disappoints. Our salt system roundup compares named units on exactly that specification, and our pump sizing guide is where your own number comes from.

3. Salt purity, which is an equipment decision. Pentair asks for salt that is at least 99.8% pure sodium chloride, evaporated, food quality and non-iodized with no additives, and warns specifically against anti-caking agents and rock salt. Hayward bans the same list. Those impurities do not get consumed — they stay in the water working on the cell. Our pool salt roundup covers which bags publish a purity figure at all.

4. Everything else metal in the water. Ladder frames, step hardware, the skimmer faceplate screws, a heater’s heat exchanger. Stainless and resin survive; plain steel does not. This is where a salt conversion quietly costs money on a pool that was not bought for it.

The numbers the makers do not agree on

Target salinity varies by manufacturer, and the differences are large enough to matter. Hayward publishes an ideal band of 2,700 to 3,400 ppm with 3,200 optimal. Intex publishes 3,000 ppm ideal within an operating range of 2,500 to 3,500. Pentair recommends 3,600 ppm and warns that above 4,500 ppm corrosion becomes a problem, with the unit shutting off below 2,600.

Pentair’s recommended level sits above Hayward’s entire ideal band. There is no universal correct salinity — only the figure in the manual for the cell you own. Anyone quoting one number for all salt pools is repeating folklore.

The picks

The Intex QZ1100 is the realistic starting point for a frame pool: it is sized for 6,000 to 15,000 gallons and publishes the pump flow range it needs, so you can check compatibility before buying rather than after.

The Hayward AquaTrol is the other end: a return-jet mounted unit rated to 18,000 gallons with a built-in timer outlet that runs your filter pump too. It is several times the price, and it suits a permanent pool rather than a seasonal one.

Pool salt is the consumable, and it is the one where the specification is simple: high purity, no additives, sold for pools. One 40 lb bag adds about 480 ppm to 10,000 gallons on the bags that publish a figure, which is how you calculate the first charge.

What a salt conversion does not change

It is still a chlorine pool — the cell makes chlorine from the salt, as our salt versus chlorine comparison explains. You still test free chlorine, pH, alkalinity and stabilizer, and salt cells drive pH upward as a matter of normal operation, so pH becomes a more frequent job rather than a less frequent one.

It also does not pay for itself quickly on a small seasonal pool. Our payback guide runs that arithmetic honestly, and the answer depends on how many seasons the pool will actually last.

Before you add the first bag

1. 1

   Confirm the wall and fittings can take it

   Resin-coated wall, stainless or resin hardware. If the pool is bare galvanized steel and you intend to keep it for years, think twice.
2. 2

   Check the generator against your pump, not your pool

   Match the published flow range the cell needs to what your pump actually delivers through the filter.
3. 3

   Work out the charge from your real volume

   Use the ppm-per-bag figure and your own gallons. Aim low and retest - the only way down is replacing water.
4. 4

   Buy salt that publishes its purity

   99.8% pure, evaporated, additive-free is what the generator manuals ask for. A bag that publishes nothing cannot be checked against that.
5. 5

   Plan for winter

   The cell comes off and comes indoors with the rest of the equipment. The salt stays in the water and does not degrade.

The conversion, in order

1. 1

   Balance the water first

   Get pH, alkalinity and stabilizer where they should be before adding salt. A cell will not fix chemistry, and it pushes pH up once running.
2. 2

   Add salt with the pump running

   Broadcast it rather than dumping it in one place, and brush it around. Give it time to dissolve fully before trusting any reading.
3. 3

   Test with something other than the cell

   Pentair notes its own salt sensor is accurate to within 500 ppm, which is a sixth of the working range. A strip or meter is the check.
4. 4

   Bring the cell on slowly

   Start at a modest output and adjust over a week against actual free chlorine readings rather than the display.
5. 5

   Watch pH weekly for the first month

   This is the change most converts are unprepared for: salt cells drive pH upward as normal operation.

What to keep testing

A salt pool is a chlorine pool, so free chlorine remains the reading that matters — CDC guidance is at least 1 ppm, or 2 ppm with stabilizer. Salinity is the new one, and it moves only when water leaves the pool. pH is the one that moves fastest.

Our testing comparison covers which method gives a usable number for each, and it is worth noting there that most digital testers infer chlorine from ORP rather than measuring it — useful for salinity, not a substitute for a chlorine test.

The parts salt reaches first

Ladder frames and step hardware, the skimmer faceplate screws, any heater’s exchanger, and the wall itself where the coating is scratched. Stainless and resin cope; plain steel is the vulnerable material, and the damage is slow enough that people attribute it to age rather than to the conversion.

If you are buying a pool with salt already in mind, our saltwater pools roundup covers which walls are specified for it, and our brand guide covers which makers publish the wall construction at all.

What it costs across three seasons

The generator is the large up-front number and the salt is close to a rounding error after the first charge, since the cell does not consume it. What people miss is the cell itself: it is a wear item with a finite life, and replacing one is a significant fraction of the price of the whole system.

That is what makes the payback arithmetic genuinely dependent on how long your pool lasts. On a permanent steel-wall pool the sums work over years. On a seasonal frame pool with a published 180-day to two-year warranty, the pool may not outlive the cell — our payback guide runs that properly rather than assuming the pool is permanent.

The other running-cost note is honest and often omitted: a salt pool still buys acid. Cells drive pH up continuously, so pH-down becomes a regular purchase where a tablet pool might need it occasionally. Set that against the tablets you no longer buy.