How Often Should I Add Salt to My Pool?

If you have a saltwater pool, you must be familiar with the fact that it is easier to maintain than a standard swimming pool. One of the ways in which saltwater pools ease the maintenance burden is by requiring less chemical management, with salt being the chief purifier. To know how many bags you should keep in your garage, you must know how often your pool will require more salt.

You should add salt to your pool once a year, usually when you replace the pool water. Any water lost in backwashing, drainage and splashing gets replaced, resulting in minor salt deficits. But aside from an annual salt boost, you will not need to add more than a pound of salt at any point.

In this article, you will learn more about managing salt in a saltwater pool, including how much is too much and whether it is better to err on the side of adding too little salt or too much of it. By the end, we will also look at how you can be sure that your pool’s salt levels are fine and the amount of salt needed in pools of different sizes. That said, it is best to start off by looking at low-salt and high-salt scenarios to illustrate the importance of knowing and following your salt targets.

If you do not add salt to your pool with the required regularity, it risks getting infested with algae and bacteria. Saltwater pools aren’t shocked as often as regular pools, which leaves room for microbes to thrive once they’re in the water for a while. 

Fortunately, the required frequency isn’t too high, and you don’t have to keep a weekly tab. The effort required is quite low, and a single reminder set on your annual calendar is all you need to not even think about your calendar anymore.

What Happens When You Add Salt too Often?

When you add too much salt to a pool, it can dehydrate your skin which can result in itchiness. This is far from an actual medical hazard and isn’t anything moisture, and a freshwater shower cannot fix. Over time, this drawback reduces as the salt gets used up and its concentration in the water decreases.

What Causes Salt Levels in the Pool to Drop?

This is one question people have when they’re told they can’t add salt just once and call it a day. After all, it is reasonable to wonder how the salt contents of a pool go down when the salt water isn’t removed from the pool. It turns out salt doesn’t have to be consumed or physically transported out of the pool. Natural operation is quite capable of reducing a pool’s salinity over time.

Salt levels in a pool drop when the saltwater gets removed from the pool, and freshwater is added to refill the pool. Sometimes, a pool has enough room, but further water isn’t added, maintaining its salinity until rain changes the concentration of salt in the pool.

Here are the three subcategories of water replacement that reduce the salinity of a saltwater pool.

Dilution of Water 

If it rains or more water is added to a pool to replace any water that is lost during everyday use, the overall amount of salt in the pool decreases. This dilution lowers the defensive shield that concentrated salt has and makes the water somewhat inhabitable for germs and bacteria.

Dipping and Leaving 

When you dive into a pool, you have no choice but to come out with some of the pool water sticking to you. This water contains salt if you’re coming out of a saltwater pool. The amount that coats your body might seem too insignificant at first, but a year’s worth of a family’s dives can add up to a few gallons of water that need to be replaced.

Closing the Pool 

Once again, since salt doesn’t break down like chlorine and doesn’t evaporate like other pool chemicals, it doesn’t get removed from the pool unless natural operation leads to the removal of water from the pool. The freshwater replacement that occurs after the pool is drained for closing creates the largest salt deficit in a saltwater pool.

How to Test if My Pool Has Enough Salt?

When the greatest risk of adding too much salt is dry skin while the greatest danger low salt levels pose is the growth of algae and bacteria, it is clear that one must err on the side of higher salt levels. But you cannot keep adding salt without having any benchmarks or measurements.

To test if your pool has enough salt, you’ll need sodium chloride testing strips or a digital reader to find the salt in Parts Per Million (ppm). The levels have to be between 2800 and 3400 pm, with 3200 being the best-balanced level. You can keep adding salt and taking new readings.

Since salt takes 24 hours to be thoroughly homogenized and evenly mixed throughout the pool, you should not rush your readings by taking them right after adding more salt. Waiting at least a few hours is advisable. 

A parts per million reading equates the quantity of water and that of salt and measures the ratio. It is one of the most accurate scales yet is easy to get wrong when the liquid isn’t homogenous. A bottle cap’s worth of water is tested, and it can have a lot of salt or be from the portion where the freshly added salt hasn’t reached.

Waiting 24 hours before each reading can be too late, so the rule of averages works better in finding out the precise salinity of the pool at short notice. Here is how you can test how much salt is in your pool water:

  1. Take a sample of the water from each corner of the pool – This diversifies the sample and reduces the error margin because the likelihood of a single salt-heavy sample creating a misleading result is much lower with multiple readings taken from the opposite ends of the pool.
  2. Take individual readings – Noting down the readings separately will allow you to notice how homogenized the water is. If the readings have a ppm difference less than 100 ppm, then the final reading can be trusted more. In contrast, if there is over a 500 ppm difference, then you should wait at least one more hour and run the pool pump before you can redo step one.
  3. Average the readings – Finally, you must take the average of the four readings. As long as the samples are within a hundred ppm of each other, you’re going to get a practically precise reading. Otherwise, you’ll need to wait and redo the process. Ultimately, the readings will need to be averaged, though.

How Can I Lower the Salt Level in My Pool?

While it is true that erring on the side of more salt is usually safer, there’s definitely a point where you need to dial it back. If the readings show 1000 ppm more salt than the recommended maximum of 3400, you should start thinking about lowering the salinity of your saltwater pool. While stews can be made less salty by adding potatoes, there’s nothing practical you can add to reduce the salinity of a swimming pool.

To lower the salt level in your pool, you need to drain a portion of the saltwater and replace it with fresh water. You can find out how much water you need to drain by looking at the levels of salt in your pool. To remove 0.2 lbs of salt from the pool, you will drain one gallon.

In ppm terms, you must get rid of one-third of your pool water in order to remove 1000 ppm of salt. The concentration in the leftover water will remain the same, but once freshwater is added, the overall ppm reading of salt will be lower because of dilution.

Salt Required by Pool Size

If you completely drain your pool during the closing season, you might need to add salt once again when you open the pool. This will be the most significant saline spike, and getting it right can save your time and energy. In this section, we will look at the amount of salt you should add depending on your pool size, so you don’t have to drain and adjust multiple times.

  • In a 12 ft x 24 ft pool (10,800 gallons), you need to add 216 lbs of swimming pool salt. 
  • In a 14 ft x 28 ft pool (14 700 gallons), you need to add 294 lbs of swimming pool salt.
  • In a 15 ft x 24 ft pool (16,875 gallons), you need to add 337 lbs of salt.
  • In a 16 ft x 32 ft pool (19,200 gallons), you need to add 384 lbs of salt.

How to Calculate the Salt When Adding it to the Pool

To make calculation easy, remember to purchase large 40 lbs bags of salt so you can weigh the bulk of the required salt by counting the bags and need to physically weigh only the last bag. Let’s elaborate on this.

Suppose you need to add 284 lbs of salt to your 16 ft x 32 ft swimming pool. It would take a long time to weigh 284 pounds of salt, so follow the steps below instead.

  1. Divide the salt target by 40, which in this instance gives you 7.1. You do this because you can easily get pre-weighed 40 lb bags of swimming pool salt.
  2. Now that you know you need to add 7.1 bags weighing 40 lbs each, you can get 8 bags of equivalent weight. AquaSalt 40lb swimming pool salt bags are Amazons’ choice for this category (more on this later).
  3. Take the whole number from the answer in step 2 (required bag quantity). In this case, you take 7 from 7.1. In this step, you will multiply the whole number by 40. This will give you the precise amount of salt in the 7 bags. That is 280 lbs in this case.
  4. Pour the calculated salt – Dump 7 bags of the swimming pool salt into the pool. Now you have added 280 lbs of salt. A further calculation is required as you subtract the salt added, 280 lbs, from the target salt (284 lbs).
  5. Weigh and pour the remaining salt – Finishing this step is as easy as weighing four pounds of salt and pouring it into the water. After this, you run the pool pump and allow the water to circulate and the salt to dissolve. It is advisable to measure the salt levels after 24 hours.

Best Salt for Swimming Pools: AquaSalt 40lb Swimming Pool Salt

A great thing about pool salt is that it is a commodity. While businesses try to brand the salt to make it look more appealing, whichever type you purchase will have the same effect as long as it is pool salt. Therefore the best thing you can do is opt for the best-priced product with significant weight per bag, which makes salt calculations above quite easy.

AquaSalt 40lb bag meets all of the above criteria. It contains 100% pure Sodium Chloride priced moderately per pound, and its ratings reflect that. With over 1000 reviews, the product has a global average rating of 4.6 stars. 

80% of its buyers have given it 5 out of 5 stars, while 11% have given it a 4-star rating. That said, if you find cheaper salt you can be sure is 100% pure, you can buy that. Avoid super-cheap open-container salt as that is mixed with other minerals and can stain your pool.

Final Thoughts

Adding salt once a year and occasionally throughout the year after it rains will take less effort than maintaining a standard pool’s chemical balance. So even though adding salt requires a bit of math and a few tests, it is far easier than what regular pools require. And as long as you get the right product, you will spend less than one does on a year’s supply of pool chemicals.

Jed Arnold

Jed spent every year from the ages of 15 - 22 as a Lifeguard (Red Cross) and ages of 17 - 22 as a Certified Pool Operator (CPO). Between working for over a dozen facilities and owning a pool, he carries over a decade of pool experience.

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