Why Is the Pool Salt Level Reading Low? 4 Causes and Fixes

Salt systems provide a low-maintenance way to chlorinate your swimming pool. If your salt cell is showing a low reading, there are several possibilities to look out for. When a pool’s salt is below the cell’s recommendation, there won’t be enough chlorine to remove algae, causing a bloom that takes a lot of work to get rid of.

A pool’s salt level is reading low because there’s not enough salt in the pool, the salt cell’s sensor is broken, the test strips are expired, or there’s not enough circulation to dissolve the salt. If you add salt to the pool and the level doesn’t change, replacing the sensor is the best solution.

Throughout this post, you’ll discover a handful of reasons your salt system is reading low levels, how you can reset the salt cell, and tips to adjust the pool’s salinity. We’ll also talk about how long a salt cell lasts and what you can do to make yours last longer.

Pro Tip: Salt systems are very reliable, but it’s worth having a backup tester in case the sensor isn’t providing the proper reading. Old, worn salt cells can deteriorate or break, so I suggest checking out the best pool salinity testers on the market. You could double-check your salt system to know if where the error is.

Why Is Your Pool Salt Level Low?

If your pool’s salt level is suddenly reading low, it won’t make enough chlorine. Without chlorine, algae will start blooming throughout the pool. The good news is you can solve this common swimming pool issue once you know which of the four problems are the culprit.

Here’s why your pool salt level is low:

1. There’s not enough salt left in your swimming pool. According to Hayward, your pool’s salt levels should be between 2700 to 3400 parts per million. If it’s lower than this range, you need to add more salt. Intentionally reducing the pool’s salt levels is a poor way to manage its chlorine levels.
2. The salt sensor might be broken or misplaced. If the sensor wasn’t installed properly, it won’t read the pool water going through the PVC pipes. Whether you have a cell rested on two 90-degree pipes or in line with the rest of the equipment, the cell needs to be completely submerged. This placement will provide an accurate reading. We’ll discuss how you can fix a broken sensor in the following section.
3. Your test strips could be expired or damaged from the sun. Swimming pool test strips are some of the most unreliable tools in the industry. After taking care of hundreds of pools, I can tell you that the drop test kits are always much more accurate and last longer. If the strips are left out in the sun or expire, they won’t read properly.
4. The salt might not be circulating throughout the swimming pool, so it won’t reach the salt cell. Check the bottom of your pool to see if there are piles of salt. This rookie mistake is caused by not brushing the pool’s floor after adding more salt. You should always use a soft brush to stir and agitate the salt when pouring a new bag.

If your pool pump is losing its pressure, it could stop the salt’s circulation. Without moving water, the salt will fall to the bottom of the pool and it won’t increase the cell’s reading. If you want to know how you can tell if the cell is working, read on.

A dirty salt cell can cause the system to have low readings. Check out this quick tutorial by INYO Pools to clean your salt cell:

How Do You Know If Your Salt Cell Is Working?

To know if your salt cell is working, use a separate testing kit to double-check the salinity levels. You can use salt test strips, drops, or a salinity kit. If you get the same reading from your second tester, you’ll know the cell is working. If not, you should replace the sensor. Raise or lower the salt percentage to see if the chlorine fluctuates with it.

If the salt cell isn’t working, your swimming pool will show low chlorine, low salt, and likely have an algae bloom. The quickest and most budget-friendly solution is to start with a tester and replace the sensor, but you might need to add more salt. If you pour another bag of salt into the pool, the levels should increase, letting your adjust the percentage that converts into chlorine.

Using the right type of salt in your pool makes all of the difference. Slow-dissolving salt won’t break down and convert into usable chlorine. The Morton Pool Salt 40-Pound Bag dissolves right as you pour it into the swimming pool. Turn on the pump, brush the bottom to agitate the salt, and the cell will return to its regular reading in no time. Make sure you use Morton’s recommendations for how much salt the pool needs based on its gallon total.

How Do You Adjust the Salt Level in Your Pool?

To adjust the salt level in your pool, add the proper amount of salt as directed by the cell’s brand, turn it up or down on the salt system’s mounted meter, and test the chlorine until it’s within the proper range. Your pool’s chlorine should be between 3ppm to 5ppm.

Some guidelines suggest chlorine as low as 1ppm, while others go up to 7 or 8ppm. In my experience, I’ve found anything below 3ppm to be insufficient for algae in warm weather and readings above 5ppm to be too strong for comfortable swimming.

Most swimming pool salt systems have a membrane button setup that lets you turn the salt level higher or lower. Pushing it up increase the chlorine and pushing it down decreases the chlorine. Contrary to popular belief, salt pools rely on chlorine! They’re not a replacement, but a different means of reaching the same chlorine levels as tablets, powder, and so on.

How Do You Reset a Salt Cell?

Royal Swimming Pools suggests resetting a salt cell by turning it off, then clicking it over to ‘Auto.’ Every salt system has different reset methods. Some of them have a button labeled ‘Reset,’ while others have a series of buttons or switches that need to be pushed. Your best bet is to contact your salt system’s manufacturer and ask how to reset it.

Keep in mind that not all problems with a salt system have to be reset. Inaccurate readings or low salt levels are often caused by bad sensors or not enough salt. Resetting the salt system won’t solve most problems so it should be used as a last resort.

How Long Does a Salt Cell Last?

A salt cell lasts between three to five years, depending on the make, model, and how well it was maintained. Cleaning your salt system involves turning off the pump, removing the cell from its unions, and scrubbing off the excess buildup. Too much salt buildup makes it much less accurate, tampering with the readings and corroding the sensors.

Much like a salt system, your pool filter can get clogged quickly. Keeping your salt system and pool filter clean will prevent the pool from turning green, red, brown, or any other color other than crystal clear.

In Conclusion

Swimming pool salt cells are designed for convenience, so it’s important to have an accurate reading as much as possible. If the reading is low, there won’t be enough chlorine to sanitize the pool and the salt cell will be ineffective.

Salt cells can last many years, but failure to clean them can half their lifespan. While some people use salt systems as supplemental sanitation, it’s crucial that it has enough salt. You can lower its percentage to reduce the chlorine levels if they’re too high.