Pool chemistry in a salt water pool involves balancing most of the same aspects as in a chlorine pool except for the salt component.
Balancing each of these components of water management ensures that your pool is clean and sanitized for healthy swimming.
Factors to balance a salt water pool
Here are the 7 main aspects of salt water pool chemistry and the ideal range to achieve. Most factors are ones that match a regular chlorine pool except salt which is only used in a salt water pool. The stabilizer amount for a salt water pool is higher than in a regularly chlorinated pool too.
ppm stands for parts per million and refers to the mass of each chemical per unit volume of the pool water.
| Water Quality Factor | Ideal Range |
| Salt | 2,700 ppm to 3,400 ppm |
| Free chlorine | 1.0 ppm to 3.0 ppm |
| pH | 7.2 to 7.8 |
| Stabilizer | 60 ppm to 80 ppm |
| Total Alkalinity | 80 ppm to 120 ppm |
| Calcium Hardness | 200 ppm to 400 ppm |
| Total Dissolved Solids | Less than 6,000 ppm |
Each aspect of salt water pool chemistry
Salt
A salt water pool relies on a salt level between 2,700 ppm and 3,400 ppm to function properly. Many chlorinators shut down chlorine production once the salt drops to around 2,600 ppm to protect the salt call from damage. The lower the salt the harder your system has to work to produce salt so you need to ensure your salt level is within range.
There are numerous reasons for salt loss in a pool but evaporation isn’t one of them so salt will need to be added to the pool from time to time.
If you have a higher end salt chlorinator from Hayward or Pentair, you can view the instant real time salt readings to keep track yourself. You can also use pool strips to monitor salt levels and take the occasional water sample to your pool store and get it checked there too.
Some chlorinator manufacturers may suggest a specific salt amount and you’ll often read 3,200 ppm as the ideal number to hit as it’s near the top end of the range and high enough away from 2,700 ppm at the low end that lack of salt won’t be a problem for awhile.
My experience: I generally add salt to the pool twice per year. Once when opening the pool (2 bags of 18 lbs each) and then again in the middle of summer (1 x 18 lb bag). I think once I had to put two bags in during the middle of summer too, but generally I put a total of three bags of salt in every pool season at a total cost of less than $20.
Tip: It’s easier to add salt to a pool than lower the salt level. Lowering the salt level quickly means draining some water from the pool and then refilling it with fresh water to dilute it so be careful when adding salt. If the salt level is marginally high you may leaves things as is because salt content will drop in a pool over time.
Free Chlorine
Free chlorine should remain in the 1 ppm – 3 ppm range for your salt water pool. Free chlorine refers to chlorine in the pool that is available (free), is unattached to any contaminants, and is thus able to sanitize pool water.
Combined chlorine refers to chlorine that has already attached itself to contaminants and is already used. Chlorine dies from use and UV rays from sunlight and thus has to be replaced hence the salt chlorinator to produce new chlorine each day.
Total chlorine is the sum of free and combined chlorine.
Test strips generally measure free chlorine as you want to know the amount of chlorine available at any given time to kill contaminants and bacteria in the water.
My experience: I generally find chlorine very easy to manage with our Hayward AquaRite chlorinator. I use test strips to measure chlorine every week or so and also take monthly water samples to the pool store to double check things. Most of the time, the pool store test shows that things are fine regarding chlorine. I run the chlorinator at 40% and have played around with the pump scheduling but tend to only run the pump 6-8 hours per day.
The main times that I have found chlorine to have dropped significantly is after a very heavy rainfall when pool chemistry tends to change as a result of diluted water.
Tip: Some pool experts will suggest a slightly higher free chlorine range of 2 ppm – 4 ppm rather than 1 ppm – 3 ppm. If you live in an area with very hot sunny weather and you have heavy pool usage you should keep the chlorine on the higher end to avoid a case where you slip close to a 0 reading and start getting algae.
pH
pH needs to remain in the range of 7.2 to 7.8. As the table above shows, water by nature is in the neutral range and baking soda is to the right of it, on the alkaline side. Baking soda can be used in your salt water pool to raise pH but you may find that having to lower your pH is actually what you experience more often than not.
My experience: I generally have little trouble keeping pH in line. I have used muriatic acid on several occasions to lower pH which is not surprising for a salt water pool. pH tends to creep up in salt water pools not because of the salt itself but because of the liquid form of chlorine that your chlorinator produces. pH can also rise due to the sudden addition of stabilizer (more on that below) or because you’re simply producing too much chlorine. Again, it’s important to keep your chlorine and other water factors in check so that they don’t knock another one out of line.
Tip: pH is a critical part of pool chemistry and is the one other than salt and chlorine that you should focus on. Each factor is important but getting the pH wrong can cause bigger trouble. While some aspects of pool chemistry can differ depending on factors like pool finish and average water temperature, the pH range is always 7.2 – 7.8.
Stabilizer
Stabilizer is also referred to by its chemical name cyanuric acid or simply CYA. It acts as a sunblock for the chlorine in your pool and protects it from the direct sun’s UV rays which can kill chlorine within hours. Some crystal chlorine products contain stabilizer but for a salt water pool, stabilizer needs to be added manually since we’re making chlorine from salt.
Stabilizer normally comes in granule or puck and its especially important to follow manufacture instructions when putting it in the pool. It typically needs to be added slowly as it can quickly coagulate and turn into a hard block that can clog pipes and be difficult to get out.
My experience: I add stabilizer to the pool once each season for the most part at the direction of the pool company. While crystal chlorine and shock products have stabilizer added, salt water pools require it added manually. I use powder form and sprinkle it very slowly directly into the side skimmer with the pump running to distribute it quickly through the pool. The important part is adding it slowly for the reason mentioned above: It has large particles, doesn’t dissolve quickly, and can clog up if you add it too quickly. After putting it through the skimmer I can see bits of it flying out the water returns in the pool still solid.
Tip: Adding too much stabilizer can be problematic as it can negatively affect chlorine and make it difficult for it to survive.
Total Alkalinity
The total alkalinity in your salt water pool should be in the range of 80 ppm – 120 ppm. Alkalinity helps to stabilize the pH in your pool so there is a relationship between the two. When the alkalinity falls below 80 ppm you can use sodium carbonate (baking soda) to increase it. To decrease total alkalinity you can use add muriatic acid or sodium bisulphate to do so.
My experience: As mentioned above, I have used muriatic acid on occasion to reduce the pH in my pool. I have also from time to time had to raise the alkalinity in my pool as well with an alkalinity increaser product. Muriatic acid is sold in liquid form and is very corrosive and dangerous. Of all the chemicals that salt water pools often require, it’s probably the most dangerous one and is clearly marked with the “extreme danger” and “highly corrosive” markings on it. Alkalinity increaser products are in powder form.
Tip: Learn about how using regular baking soda in your salt water pool can help to increase alkalinity in your pool without using a harsher chemical product that also tends to be more expensive.
Calcium Hardness
The calcium hardness range for your salt water pool is 200 ppm – 400 ppm. Water hardness is another important aspect of water chemistry to get right and happens to be one that water itself tries to fix it you don’t: If your water is lacking calcium and becomes too soft, the water will try to find its own source of calcium from metal fittings, the ladder, parts of your pool and other metallic equipment. This is the corrosive effect that water has when its not balanced.
At the other end of the spectrum, if water is too hard it becomes cloudy and the will develop scale. This can lead to the water flow being blocked and the damage of pool equipment occurring.
My experience: If you have a water softener in your home, you’re probably already familiar with soft and hard water. Salt is used in a water softener to remove calcium and magnesium from your water to make it softer on your skin, hair and clothing. In your pool, you need to balance the hardness of water and in my experience, I’ve never had a problem. It’s one of the factors that seems to be easy for me to maintain.
Tip: You increase hardness of water by adding a product like calcium chloride. You can’t decrease water hardness in a salt water pool with any specific chemical. Draining some water from your pool and filling it with softened water from your water softener may help but it’s best to check with your pool company first in this instance.
Total Dissolved Solids
Total dissolved solids in water generally refer to minerals like calcium, magnesium and sodium but in a pool it also refers to literally anything else that was once solid that dissolved in your pool water such as algae, leaves, twigs, dust, pollen and human waste.
Total dissolved solids in distilled water is 0. Drinking water should have total dissolved solids of under 500 ppm. With a salt water pool using salt in the range of 2,700 ppm – 3,400 plus calcium and other dissolved solids existing, it isn’t difficult for total dissolved solids to reach levels of of 5,000 ppm and more.
My experience: I can’t recall total dissolved solids ever being a problem for me nor can I ever recall my pool company even mentioning it to me. I vacuum the pool regularly. I rinse my pool cartridge filter mediums regularly. I pay attention to water chemistry and keep it balanced. Given that we live in a cold winter environment, we drain the pool below the jets every autumn when the pool is closed so significant water is being replaced yearly.
Tip: The traditional way to reduce total dissolved solids in your pool is to drain some of the water and replace it with fresh water from your garden hose. Proper maintenance and occasional draining of the pool is key to keeping dissolved solids in line and if you drain part of the pool during closing you might find that does enough.
Other chemicals I use in my salt water pool
Other than squirting a blue clarifier in the pool now and then, I don’t use any other chemicals other than the ones mentioned above except for the following:
Algaecide: Occasionally green algae has been a problem for me particularly in spring when opening the pool so I have used a bottle of algaecide to fix it when needed.
Muriatic acid: As mentioned above, I have occasionally used muriatic acid for total alkalinity balancing. I recall when we bought our house, the previous owner left a half empty bottle of it among the pool supplies so that was my first hint it was going to be used.
Filter cartridge cleaner: It took me several years of pool ownership before I discovered the benefits of a filter cartridge cleaner. While filter mediums (the pleated cartridges) get dirty and full of contaminants, they need to be rinsed perhaps once or twice per pool season. I found that popping them in a large bucket with a $10 bottle of cartridge cleaner that I bought at Walmart made a huge difference over simply water rinsing them. A filter cleaner can help to better remove oil and other debris and make your filtration system run more effectively by helping contaminants attach to the pleating and remain out of the pool water.
Main reasons why salt water pool water chemistry gets unbalanced
Occasionally water balance will fall out of line in your salt water pool and it’s good to know about why this happens. While you can’t always prevent it from happening, knowing why it happens can help you deal with it proactively the next time.
Here are some common reasons:
- Heavy pool usage
- Sudden spike in sun and elevated water temperature
- Heavy rainfall
- Draining and refilling the pool water
- Evaporation, leaks, or other significant water loss that requires refilling
- Backwashing your sand filter
- Chlorinator breaks and stops working
- Poor water flow and circulation
- Algae break out
- Chlorine lock
- You try to change one aspect of water chemistry in your pool but it impacts another ie. you use baking soda to raise pH but then raise alkalinity too.
This is a short list but includes the main ones you’re likely to face over time.
Check out my salt water pool chemistry chart for specific ideas regarding how to correct water imbalances.