A saltwater pool still uses chlorine. The difference is that a salt chlorine generator makes it for you from dissolved salt. To do that, the water has to hold the right amount of salt, and that is where most new owners have questions. How much do I add? Where do I pour it? How long before I turn the system on?
This guide walks through the math, the steps and the upkeep so you can add pool salt with confidence.
How a Salt Chlorine Generator Works
Water passes through a cell with charged plates. The cell converts some of the dissolved salt into chlorine, which sanitizes the pool. As the chlorine does its work, it returns to salt, so the salt level stays fairly steady. You lose salt mostly through water leaving the pool: backwashing, splash-out, draining and overflow from heavy rain.
Every generator has a target salt range listed in its manual. If the level is too low, the cell may produce less chlorine or show a warning. Too high, and some systems also shut down or flag an error. The goal is to land inside that range.
How Much Salt Does Your Pool Need?
You need two numbers: your pool volume in gallons and how many parts per million (ppm) of salt you need to add. A gallon of water weighs about 8.34 lb, so 1,000 gallons weighs about 8,340 lb. One ppm of that is about 0.00834 lb. That gives a simple rule:
Pounds of salt = gallons ÷ 1,000 × 8.34 × (ppm to add ÷ 1,000)
Test your current level first, then subtract it from your target. The table shows examples for a pool starting with no salt and a target of 3,200 ppm. Use your own generator's target in place of that number.
| Pool volume | Salt to reach 3,200 ppm from 0 | Approx. 40 lb bags |
|---|---|---|
| 10,000 gallons | About 267 lb | 7 |
| 15,000 gallons | About 400 lb | 10 |
| 20,000 gallons | About 534 lb | 14 |
| 25,000 gallons | About 667 lb | 17 |
| 30,000 gallons | About 801 lb | 20 |
If you are topping up rather than starting from zero, the numbers are much smaller. A 20,000 gallon pool reading 2,700 ppm with a target of 3,200 ppm needs about 83 lb, or about two 40 lb bags. It is easier to add a little more later than to drain water to bring a high level down, so round down when in doubt.
Choosing the Right Pool Salt
Use high purity sodium chloride made for pools, with no iodine and no anti-caking agents. Those additives can stain surfaces or leave residue. Finer crystals dissolve faster, while coarser salt may take longer to disappear from the pool floor, so brushing matters more with larger grains. Store unopened bags somewhere dry, since damp salt can clump and be harder to spread evenly. Most pool salt comes in 40 lb bags, which keeps the math easy.
- Sunkissed Pool Salt, High Purity, 40 lb
- Cargill Pool Salt, Crystalline, 40 lb
- Chemical Equipment Labs Swimming Pool Salt, 40 lb
- Morton Pool Salt, 40 lb
- CrystalPure Pool Salt, 8 lb for small top-ups
Do not use rust remover softener salt or de-icing rock salt in a pool. Both contain materials you do not want in the water.
How to Add Salt to Your Pool, Step by Step
- Test the water. Check the salt level with a test strip or meter, and balance pH and alkalinity first.
- Turn off the generator. Leave the pump running so the water circulates.
- Pour the salt around the shallow end and perimeter. Spread it out rather than dumping it in one pile, and keep it away from the skimmer.
- Brush the salt. Sweep undissolved salt off the floor toward the main drain so it does not sit on the surface.
- Circulate. Run the pump for about 24 hours so the salt dissolves and mixes evenly.
- Retest, then turn the generator back on. Confirm the level is in range before you restart the cell.
How to Find Your Pool Volume
The salt math only works if the volume is right. If you do not know your pool's gallons, check the builder's paperwork or the generator installation records first. Otherwise, you can estimate with a tape measure. These are common rule-of-thumb formulas, and they give a close enough starting point for adding salt in steps.
- Rectangle: length × width × average depth × 7.5 = gallons.
- Round: diameter × diameter × average depth × 5.9 = gallons.
- Oval: long diameter × short diameter × average depth × 5.9 = gallons.
Measure in feet. For average depth, add the shallow and deep end depths and divide by two. Because these are estimates, add about three quarters of the calculated salt first, circulate, test and then add the rest as needed.
Keeping the Salt Level Right All Season
Test salt regularly during the swim season and after big weather or water changes. If the reading drops, add a small amount and retest after circulation. If it reads high, the only fix is to replace some water with fresh water, which is why careful math up front pays off.
Keep an eye on the generator cell too. Scale can build up on the plates, especially with hard fill water, and a dirty cell can give low readings or produce less chlorine. Inspect and clean it as your manual directs, and confirm a low display reading with a separate test before adding salt.
Opening season is when most owners buy the bulk of their salt for the year. If you manage several pools, a pallet of 40 lb bags can be simpler than repeat trips. Pallets ship by LTL freight, and we quote the freight through our bulk pallet orders page.
Frequently asked questions
How many bags of salt do I need for my pool?
Multiply your pool volume in thousands of gallons by 8.34 lb for every 1,000 ppm you need to add, then divide by the bag size. A 20,000 gallon pool going from 0 to 3,200 ppm needs about 534 lb, or about 14 bags of 40 lb salt.
Can I use water softener salt in my pool?
Pool salt is the safer choice. Softener pellets can contain binders and additives, and rust remover salt should never go in a pool. Use a high purity pool salt unless your generator maker says otherwise.
What kind of salt is best for a saltwater pool?
High purity sodium chloride made for pools, without iodine, anti-caking agents or other additives. Your salt chlorine generator manual may list a minimum purity.
How often do I add salt to my pool?
Salt does not evaporate, so you mainly add it after refilling, heavy rain, backwashing or splash-out. Test regularly during the season and top up when the reading drops below your system's range.
What should my pool salt level be?
Follow your chlorine generator's recommended range. Many residential systems fall in the 3,000 to 3,500 ppm area, but models differ, so check your manual.
Shop high purity pool salt in our pool and spa salt collection, or see bulk and pallet orders if you are stocking up for opening season. More answers are on our FAQ page, and you can reach us anytime through our contact page.
