How Much Salt Should I Add to My Pool?

In Blog, Chemistry, Salt by David Jerkins

Maintaining the proper salinity levels in your pool or spa is paramount when running a chlorine generator. If you run the salinity too high or low, you could damage your equipment.

The key to determining how much salt to add to the pool is:

[Volume of Pool] x 8.35 x [desired increase in thousandths] = pounds of salt to add.

Example: I have a 15,000 gallon pool. I just filled it, so there is no salt in it. According to the manual for the chlorine generator, I need to maintain 3500-4500 ppm salinity in the pool so I target 4000 ppm. That would look like:

15,000 x 8.35 x 0.004 = 501 lbs of salt is needed to reach 4000 ppm. Add 13 bags of pool salt.

Remember, it ultimately depends on what the equipment demands. Always check manufacturer’s guidelines, which should indicate a minimum and maximum for salinity. In most cases, that will be 3500-5000 ppm. If the manual states that salinity should be between 3500-4500 ppm for best results, target right in the middle: 4000 ppm.

If your 10,000 gallon pool already has salt in it, keep that in mind. If you test the pool, and it has 2300 ppm salinity, and your goal is 3500, you only need to increase it by 1200 ppm. That would be 0.0012 in thousandths in the formula. Therefore: 10,000 x 8.35 x .0012 = 100 lbs of salt needed.

Pool Salt always comes in 40 pound bags, so just divide the result by 40 to figure out how many bags you need to add.

Don’t dump the salt in one place! Spread bags out around the pool and distribute it in different locations. After that, brush the salt that settles at the bottom of the pool towards the main drains to speed up the process. It may take a turnover before all of the salt is circulated throughout the pool. Wait a few hours at least before testing again.

An important note on salinity for chlorine generators. If salinity is too low, it can and will damage the equipment. The cells in the chlorine generators are taking that salt and converting it to chlorine for the pool. If there’s not enough salt, the cells work harder, increasing wear and tear on them and shortening the lifespan of your equipment. By maintaining proper salinity levels consistently, you can increase the life of your equipment.

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How to Tell How Many Gallons are in Your Pool