Salt (NaCl)
Salt in a pool is sodium chloride (NaCl) dissolved at 2700–3400 ppm so that a salt water generator can use electrolysis to produce hypochlorous acid — the same active sanitizer as adding liquid chlorine. A salt pool is a chlorine pool that makes its own chlorine from salt.
Salt level target ranges
Most salt water generators target 2700–3400 ppm. Always confirm with your cell manufacturer — operating ranges vary by brand and model, and running outside them reduces cell life.
| Salt level | Status | Notes |
|---|---|---|
| Below 2700 ppm | Too low | Most cells alarm here; reduced output or shutdown; top up before running |
| 2700–3400 ppm | Target range | Aim for the midpoint your cell specifies; ~3000–3200 is common |
| 3400–4000 ppm | High | Acceptable for some cells; may trigger high-salt alarm; slight salty taste |
| Above 4500 ppm | Too high | Stresses cell plates; chloride corrosion risk on metal fittings and heater |
For reference: pool salt at 3200 ppm is about 1/10th the salinity of ocean water (~35,000 ppm). The water has a faint softness compared to a traditional chlorine pool but is not noticeably salty to most swimmers.
How a salt water generator works
A salt water generator (SWG), also called a salt chlorine generator (SCG), passes pool water over a pair of electrolytic cell plates and runs a low-voltage electrical current through them. The current splits the dissolved sodium chloride and water into hypochlorous acid (HOCl) — the active form of chlorine that sanitizes. The sodium recombines with the byproducts and the process repeats, which is why salt consumption is very low once the pool is at level.
Salt pools still need all the same water balance
A SWG handles chlorine generation but does nothing to control pH, alkalinity, calcium hardness, or CYA. These still need to be tested and adjusted manually. In fact, electrolysis slightly raises pH over time — SWG owners often need to add acid more frequently than non-SWG pools.
Salt and the FC/CYA ratio
Because a SWG produces chlorine continuously rather than in one large dose, it maintains a steadier FC level throughout the day. This continuous production changes the minimum FC requirement: SWG pools use a minimum of FC = CYA × 5% rather than the 7.5% rule for non-SWG pools.
At CYA 70, that means a minimum of 3.5 ppm FC for a SWG pool vs. 5.25 ppm for a non-SWG pool. The target range stays the same — only the minimum floor changes. CYA still needs to be managed: if CYA climbs too high, the SWG has to run longer to maintain adequate FC, and cell wear increases.
Salt and LSI: why it matters more for SWG owners
Salt cell plates run hot during electrolysis — they are the highest-temperature surface in the system. When LSI is positive (scale-forming), calcium carbonate deposits preferentially on those hot plates, coating the electrode surface and reducing electrolytic efficiency. Even a mildly positive LSI that causes no visible scale on plaster surfaces will shorten cell life noticeably over a season.
SWG owners should target a tighter LSI range than non-SWG pools. A comfortable target is LSI 0.00 to +0.10 rather than the wider ±0.3 range acceptable for non-SWG pools. This means keeping calcium hardness, total alkalinity, and temperature in close balance.
Scale in a salt cell is an LSI problem, not a salt problem
If white deposits form on your cell plates, the cause is positive LSI — usually high calcium, high alkalinity, or high pH. Adding a descaling acid wash fixes it temporarily, but the deposits will return until the water balance is corrected. See how to diagnose and prevent salt cell scale →
How to raise salt
Add pool-grade sodium chloride — sold as “pool salt” or solar salt (plain white crystals, no additives, no yellow prussiate of soda). As a rough guide, 8 lbs per 10,000 gallons raises salt by about 100 ppm. Broadcast it slowly around the perimeter with the pump running; it dissolves within a few hours in warm water.
Always retest before adding more. Salt test strips and inline SWG sensors are both reasonable checks, though a liquid drop test or digital meter gives the most reliable reading. Do not rely solely on the SWG’s onboard display — salt cells can misread after calcium scale buildup on the sensor.
How to lower salt
There is no chemical that removes salt. The only option is to drain some water and replace it with fresh water. Salt does not evaporate, degrade, or get consumed by the electrolysis process — the only way it leaves the pool is with the water itself (backwashing, splash-out, or draining).
Salt that rises slowly over time is usually from fill water, chemical additions (some chlorine forms add salt), or evaporation concentrating what was already there. If salt is creeping up season after season, a partial drain in spring is the most direct fix.
Want to...
Track salt level alongside all your water balance parameters
PoolChem Tracker logs salt, FC, pH, alkalinity, calcium hardness, and CYA — and calculates your LSI automatically every time you test. For SWG owners, keeping LSI in check is the single best way to protect your cell.
