Pool Salt Calculator: How Much Salt Should You Add? (Easy)


by Rick Patterson

Dosing your pool water with the correct amount of sanitizer can be tricky. 

With saltwater pools, a salt overdose rarely leads to major issues, but learning to add the proper amount will save you from potential headaches.

As pools come in various sizes, shapes, and depths, we’re here to help you figure out how much salt to add for the perfect level of pool sanitizer every time.

Why Salt Level Matters

Many people don’t realize that saltwater pools still use chlorine in their water, but how the chlorine is added to the pool is where things differ.

Salt is first added to the water, and a salt chlorine generator (also called a salt cell or saltwater chlorinator), uses electrolysis to split the salt molecules, turning them into chlorine.

Too little and your salt generator won’t be able to make enough chlorine, which means your pool won’t be clean enough to swim in. Too much and you end up with salty tasting water, not to mention it can potentially corrode metallic surfaces.

The ideal level for salt in a saltwater pool is 3200 ppm, but between 2700 and 3400 ppm is also acceptable.

Pro tip: Only use sodium chloride (NaCl) that has a purity of 99% or higher. Any other salt will not only make the chlorine less effective, but you run the risk of discoloring your pool finish, surfaces, and fittings of your pool.

How To Calculate The Amount Of Salt Needed

Now that you know you’re aiming for 3200 ppm, you need to figure out how much salt that will translate to for your pool.

Step #1: Get Your Current Salt Level

First things first, you need to test your pool water for its current salt level. This can be done easily with specialized salt test strips, a saltwater liquid test kit, or with a digital tester that measures for salinity.

The best way to test is by dunking a glass of water elbow deep in the deep end of your pool. You can then take the water sample and subject it to whichever testing method you prefer.

For pinpoint accuracy, you may even want to bring the sample to a pool shop where they can measure the salt level (usually for free!).

Step #2: Get Your Pool Water Volume

Nex, figure out the amount of water in your pool. If you built your pool from scratch then you probably know this number off by heart. The majority of backyard pools fall somewhere between 10,000 and 20,000 gallons.

If you don’t know, you can use an equation to figure it out.

  • Rectangular Pools: Length x Width x Average Depth x 7.5 = Volume (in gallons)
  • Circular Pools: Diameter x Diameter x Average Depth x 5.9 = Volume (in gallons)
  • Oval Pools: Length x Width x Average Depth x 6.7 = Volume (in gallons)

For example, if you have a large rectangular 32 foot x 16 foot pool, with a 4 foot depth in the shallow end, and 8 foot depth in the deep end (average depth of 6), the water volume will be 23,040 gallons.

Step #3:  Crunch The Numbers

Now that you know the pool water’s current salt level, and you know the water volume of the pool, you can consult a pool salt chart to give you the exact amount of salt you’ll need to add to the pool.

For instance, if a 23,040 gallon pool was getting its initial dose of salt, you would need 587 lbs. of it to raise the level from zero to 3200 ppm. Considering pool salt comes in 40 lb. bags, you’d need almost 15 bags – but at around $7 per bag, it’s not too expensive to keep up after your first dose.

Additionally, you can also crunch the numbers using a pool calculator, which will tell you the precise amount of salt needed.

How To Add Salt To Your Saltwater Pool

Adding salt to a swimming pool is pretty much as easy as it sounds, but there are a few nuances to be aware of.

Here’s how to do it:

  1. Start by testing and balancing your pool water. You want to aim for a pH level between 7.4 and 7.6, and between 80 and 120 ppm for total alkalinity. Don’t forget to test your salt level! 
  2. Calculate how much salt is needed for the pool using the process outlined above. 
  3. Test for salt levels once more. The water’s salinity can fluctuate in cold or hot weather. For this step you should take a sample and let it adjust to room temperature before testing it. If it’s wildly different from the level in step 1, adjust your calculations.
  4. Turn off the pool’s chlorine generator. This will allow for the salt to be evenly distributed throughout the pool by the pump.
  5. Pour the salt directly into the pool but away from the skimmer.
  6. Brush down the pool floor, as large amounts of salt can settle there
  7. undissolved. Brushing toward the main drain(s) will help move the salt through the pool’s system for faster dispersion.
  8. Keep the pump running for at least 24 hours. Large pools may require 48 hours for all of the salt to dissolve and be distributed.
  9. Retest the salt levels in the water.
  10. Repeat the process if the pool needs more salt.

How To Dilute Your Saltwater Pool

For the times where you’ve made a calculation error (hey, it happens to the best of us) and the pool has too much salt, there is only one way to reduce it – through dilution.

Diluting pool water is a bit of a pain, but you should only ever do partial draining of the pool. If you take out too much water, you run the risk of having the pool pop up out of the ground. 

Here’s how to do it:

  1. Start by testing the water so you have an idea of how much water you may need to remove to bring the salt level down to 3200 ppm.
  2. Turn off the pool’s filtration system. This is to protect the equipment from damage, as air can be sucked in through the skimmer if there’s an inadequate water level.
  3. Attach a hose to a submersible pump. Place the pump in the deep end of the pool and run the hose to a sewer or safe drainage point. 
  4. Turn the pump on. Drain the pool only a few inches. 
  5. Connect a garden hose to your backyard spigot and fill up the pool to the halfway mark of the skimmer.
  6. Test the water to see where your salt levels are at.
  7. If you need to, repeat the process until your salt levels are near 3200 ppm.
  8. Turn the pool system on so it can circulate the fresh water into the pool through the return jets. This may take several hours.
  9. Retest your salt levels in the pool and make adjustments to the water if needed.

Feeling Salty Yet?

Figuring out the amount of chemicals a pool needs can be confusing, but calculating how much salt to add isn’t too difficult.

The only thing you’ll need to be careful of is adding too much. But with the right calculations, you shouldn’t have any problems and will be a salt pro in no time.

Categories: Pool Care, Pool Chemistry