Pool salt is one of the most commoditized products in the industry — sodium chloride is sodium chloride. But not all bags marketed as "pool salt" contain the same product, and the differences in purity and additives have real consequences for your salt chlorinator and pool water quality.
Pool-grade sodium chloride needs to be at minimum 99.8% pure NaCl. Food salt, road salt, and many water softener salts contain anti-caking agents, iodine, potassium ferrocyanide, or other additives that can cloud pool water, interfere with salt cell electrolysis, or accelerate cell plating corrosion. The bag needs to be free of those additives — that's the primary differentiator.
Beyond purity, granule size matters. Fine-grain salt dissolves faster but can cloud the water temporarily during addition. Coarser granules (sometimes called solar salt) dissolve more slowly but add more cleanly. Most pool-specific brands use medium granule size as a compromise.
| Brand | Purity | Price (40 lb bag) | Notes |
|---|---|---|---|
| Clorox Pool Salt | 99.8%+ NaCl | ~$9–12 | Wide availability, consistent quality |
| Morton Pool Salt | 99.9% NaCl | ~$10–13 | Premium purity, low insoluble content |
| BioGuard Pool Salt | 99.8%+ NaCl | ~$12–15 | Pro distribution, reliable sourcing |
| In The Swim Pool Salt | 99.8% NaCl | ~$8–11 | Good online value, same chemistry |
| Diamond Crystal Solar Salt | 99.6% NaCl | ~$7–9 | Slightly lower purity, widely available |
Clorox pool salt is the default recommendation for most residential salt pool owners because it's available at nearly every big-box home improvement store. At 99.8%+ purity with minimal additives, it performs well in all major salt chlorinator brands including Hayward AquaRite, Pentair IntelliChlor, and Jandy TruClear. A 40-lb bag typically runs $9–12. For a 20,000-gallon pool needing 500 lbs to reach 3,000 ppm, expect 12–13 bags for initial fill.
Morton's pool-specific salt product specifies 99.9% NaCl with very low insoluble content. That extra 0.1% sounds minor, but lower insoluble content means less clouding during addition and less sediment accumulation on the pool floor. For high-end residential accounts and commercial pools, Morton is the premium pick. The price premium over Clorox or generic brands is small.
In The Swim sells 40-lb bags through Amazon and their direct site at prices that often undercut local retail, especially when bought in pallet quantities for service companies. At 99.8% purity, the chemistry is identical to premium brands. This is a solid option for service companies maintaining multiple salt pools and buying salt in volume.
Never use iodized table salt, road de-icing salt, or agricultural salt in a pool. These contain additives that will stain pool surfaces, damage equipment, and compromise water chemistry. Only use salt specifically labeled for pool use or verified 99.8%+ pure NaCl without additives.
Most salt chlorinators target 2,700–3,400 ppm of salt. Use this formula to estimate initial salt needed:
Pounds of salt = (Target ppm − Current ppm) × Pool gallons ÷ 1,000,000 × 8.34
For a 20,000-gallon pool starting at 0 ppm and targeting 3,000 ppm:
(3,000 − 0) × 20,000 ÷ 1,000,000 × 8.34 = 500 lbs (approximately 12–13 bags of 40-lb salt)
After adding salt, run the pump for 24 hours before testing salinity and turning on the chlorinator. Salt distributes unevenly if tested immediately after addition. Use a digital salt meter rather than strips for the most accurate reading, and log the result in SplashLens so you have baseline data for every future visit.
Your salt cell is where sodium chloride gets converted to chlorine via electrolysis. Cell plates accumulate calcium and mineral scale over time, reducing efficiency and eventually requiring replacement. Higher-purity salt reduces the rate of scaling. When inspecting cells, look for white mineral buildup on the plates — clean with diluted muriatic acid when scale is visible. Log cell inspection dates and condition in your service app so you have maintenance history for each salt pool account.
SplashLens lets you log salt readings, cell inspections, and chemical additions for every salt pool on your route. Free and offline-first for pool service professionals.
Open SplashLens Free →Pool salt should be at least 99.8% pure sodium chloride (NaCl). Anti-caking agents and other additives in food-grade or water softener salt can interfere with salt chlorinator function or cause cloudiness.
Some water softener salts are acceptable if they are 99.8%+ pure NaCl without anti-caking additives. However, pellet-form softener salts dissolve slowly and can accumulate on the pool floor. Solar salt (evaporated sea salt) is generally preferred.
Most salt chlorinators require 2,700–3,400 ppm of salt. A 20,000-gallon pool starting from zero needs approximately 500–600 lbs of salt to reach the target range. After initial fill, salt is only added to compensate for water loss from splashing, backwashing, and rain dilution.
Salt doesn't evaporate, but it leaves with water. Expect to add 10–20% of the initial salt charge each season to compensate for water replacement, backwashing, and splash-out. Test salinity monthly with a digital salt meter or dedicated test strips.
High-purity pool salt reduces scaling and mineral buildup on salt cell plates, which extends cell life. Impure or additive-laden salts accelerate cell fouling. The cost difference between budget and quality pool salt is small compared to the cost of salt cell replacement.