Maybe you’ve built a new pool in your backyard and need to find out how to fill a saltwater swimming pool. Or perhaps you’re thinking about converting your freshwater pool to saltwater. Salt water pools are the preferred option for many pool owners because they are low maintenance and inexpensive to operate.
When you operate a swimming pool you have two options – freshwater or saltwater. A freshwater pool can be sanitized with chlorine, biguanide, ozone or ion cleansing. Saltwater pools are sanitized automatically with chlorine generated from a saltwater chlorinator unit. The chlorinator cell is the last item of equipment in a pool filtration system. It’s connected into the plumbing after the filtration unit and water heater.
When the filtration system is operating the filtered pool water passes through the chlorinator unit where a low voltage electric current is applied to an electrolytic cell that splits the salt into chlorine which instantly dissolves in the pool water. The dissolved chlorine kills bacteria, viruses, algae and other contaminants in your pool which are later trapped in your filter.
Table of Contents
How to Fill a Saltwater Swimming Pool
- Fill with fresh water
- Add Salt
- Add Stabilizer
- Circulate the water with the pump
- Balance water chemistry
How to Add Salt to a Pool
Adding Salt for Marble Plaster Surface Pools
When you fill a saltwater swimming pool do not add salt to new concrete pools with a marble plaster finish until the excess calcium compounds in the plaster have leached out and the pH of the water has stabilized. The recommended stabilizing period is a minimum of 12 weeks. During this time the chlorinator unit is switched off and the pool is run as a fresh water pool and should be sterilized manually with liquid chlorine or tablets.
What type of Salt do I Use?
Only use proper swimming pool salt (sodium chloride) that is designed to be used with a salt water chlorinator unit. Inferior grades of salt will cause the chlorinator to not operate effectively leading to reduced chlorine output and an unsanitized pool.
How much salt do you put in a saltwater pool?
The level of salt concentration that you have in your pool depends on the chlorinator manufacturer’s specifications. Most chlorinators operate with a salt concentration of 3000 to 7000 mg/l (ppm).
However, with outdoor pools in sub-tropical and tropical climates and heated pools the recommended salt level should be increased to 5000 to 7000 ppm in order to increase the chlorine output to compensate for the extra chlorine evaporation from the pool.
Add the recommended amount of salt for the volume of your pool.
Water volume (m3) = (Surface Area (m2) x Average Depth) – (Volume of steps, cutouts, etc)
1 cubic meter = 1000 litres of water
Salt quantity (kg) = water volume (m3) x Salt Concentration (mg/l) / 1000
Example
Volume = 60 cubic metres (60,000 litres)
Desired Salt concentration = 5000 ppm (mg/l)
Salt quantity (kg) = 60 x 5000 / 1000 = 300kg
Salt comes in 20kg bags, so you need 15 bags of pool salt.
How to Fill a Saltwater Swimming Pool & Add the Salt
Once you have calculated how many bags of salt you need for the volume of your pool you need to add the salt to the water.
Do not add salt into the skimmer box as this will clog your plumbing, increase pressure and potentially damage the filtration system.
Turn on your pump with the chlorinator switched off.
Place the bags of salt evenly around the edge of your pool. Cut open each bag and empty the contents into the pool water.
At the same time add the recommended amount of pool stabilizer (cyanuric acid) into the pool. It’s important to add stabilizer especially during summer to slow the evaporation of chlorine from the pool. Your saltwater chlorinator unit may not operate efficiently without the correct level of pool stabilizer dissolved in the water. The recommended level is 30 to 60 ppm. The start-up quantity of stabilizer will be around 2kg for a normal inground pool.
Use your pool brush on the long pole to push the salt around the pool until it is dissolved. You will need to repeat this a few times.
Operate the pump for a complete cycle to fully dissolve the salt and stabilizer. A complete cycle is when the pump has pumped over the entire contents of the pool which usually takes at least 8 hours (depending on your pump).
The following day when all the salt has fully dissolved switch on the chlorinator unit to start generating chlorine.
How long after putting salt in a Pool can you swim?
It’s never recommended to swim in a pool when salt or chemicals have just been added. You need to wait for one cycle of the pump to fully dissolve and circulate the salt or chemical before swimming in the pool.
Saltwater vs Freshwater Pools
Which is better a salt water pool or chlorine?
All saltwater pools contain chlorine as it is produced by the chlorinator unit to sanitize the pool. However, the chlorine level in saltwater pools is lower than a freshwater pool because the chlorinator unit is constantly generating chlorine throughout the day and night whenever the pump is running. So salt pool water will be gentler on your skin, eyes and swimwear.
Freshwater pools are chlorinated with higher doses of chlorine because the chlorine quickly evaporates from the water and you need more of it to last longer. You need to purchase chlorine liquid of tablets to sanitize the pool which is expensive.
Does a Saltwater Pool use more Electricity?
All swimming pools need to be filtered by running a pump which costs money. Adding a chlorinator unit into the plumbing does not affect the pump at all so makes no difference to the amount of electricity usage. The chlorinator cell uses a low voltage current to split the salt into chlorine which will add a small extra cost to your power bill. However, using a chlorinator means you don’t have to buy chlorine and some other chemicals for the pool saving you money.
Do you shock a salt water pool?
Yes, you still need to shock the pool water to kill all bacteria and algae.
How Salty is a Saltwater Pool?
Pool salt is purified crystallized common salt made from sodium chloride. The concentration of salt is 3000 to 7000 mg/l (ppm) for a saltwater pool which is only about 10 to 15% of the salt found in seawater (35,000 ppm). The concentration of salt in a pool is about equal to the salinity of the tears in your eyes so opening your eyes underwater will be perfectly comfortable.
Saltwater Pool
- The chlorinator automatically produces chlorine
- Water is gentler on skin, eyes and swimwear
- Less expensive to run
- Need to purchase the chlorinator unit
- Chlorinator cells last about 5 years
Freshwater Pool
- Need to purchase chlorine or other sanitizer
- Manually add chlorine or use an auto dispenser
- Usually need a higher dose of chlorine than salt water
Do you have to shower after salt water pool?
I recommend to always shower after swimming in any pool to remove excess salt, chlorine and other chemicals from your skin and always rinse out your swimwear.
Please read our article on Should You Shower Before You Swim?
Saltwater Pool Maintenance
Can you put too much salt in a saltwater pool?
Yes, when you fill a saltwater swimming pool you can add too much salt to the pool. This may cause the chlorinator unit to not operate effectively leaving the water unsanitized. If there is too much salt in the pool water you need to dilute the water by draining some of the water and refill the pool.
Can you put chlorine tablets in a saltwater pool?
Yes, you can use chlorine tablets, liquid chlorine or granular chlorine in a salt water pool if required. This is normal when you first start up a salt pool because you may not be able to add the salt until the pool surface has fully cured as with plaster and paint. If ever the saltwater chlorinator has not generated enough chlorine you may need to manually add additional chlorine.
Do I need to add extra salt every year?
Yes. You will find that the chlorination process consumes salt from your pool and every 6 months you will need to add a bag of salt to maintain the desired level of salinity in the pool water.
How long should I run my salt chlorinator?
Typically, run your pool pump and chlorinator for up to 8 hours a day depending on the capacity of your pump. In the winter reduce the hours to 5 or 6 hours a day. Normally you split the pump time into two sessions of 3 or 4 hours each.
How much chlorine should be in a saltwater pool?
A salt water pool must have 1 to 3 ppm of free chlorine to ensure the pool is adequately sanitized. If the chlorine is too high reduce the pump time and/or turn down the chlorinator to produce less chlorine. If the chlorine is too low turn up the chlorinator and run the pump longer. You can also manually add extra chlorine to increase the level.
Conclusion
Now that you have learned how to fill a salt water swimming pool it’s time to activate the saltwater chlorinator.
My personal experience is with salt water pools for over 30 years. I recommend saltwater chlorination because it not only works very well but it’s inexpensive to install, operate and maintain. A saltwater pool virtually looks after itself on autopilot.
The salt water concentration is very low similar to saline solution for washing your eyes so it cannot irritate you skin or eyes. And you can hardly taste the salt in the water. Other sanitation options are more complex, expensive and require more of your time to operate effectively.