You have a freshwater pool and you’re thinking about how to convert your pool to salt water. Well don’t think too hard because the conversion to salt water is easy. Salt water swimming pools and spas are the preferred option for many pool owners because they are low maintenance, use less chemicals and inexpensive to operate.
A freshwater swimming pool is converted to a salt water pool by adding bags of pool salt and installing a chlorinator unit. Saltwater pools are automatically sanitized with a low level of chlorine produced from a salt water chlorinator cell. There is no need to manually add chlorine or any other sanitizer to the pool. The chlorinator cell is always installed as the last item of equipment after the pool filter and water heater.
When the filtration system is running the salt pool water passes through the salt water chlorinator unit where an electrolytic cell splits the salt into chlorine which instantly dissolves in the water. The free chlorine kills bacteria, viruses, algae and other contaminants in your pool water.
Table of Contents
Why Convert Your Pool to Salt Water?
There are many good reasons to convert to salt water chlorination.
- A salt water swimming pool is automatically sanitized by a saltwater chlorinator cell so you don’t have to add chlorine. The chlorine from a cell is higher quality than from tablets or granules.
- Chlorination consistently produces free chlorine every time the pump is running.
- Salt water requires less chemicals added to the pool.
- The pool water is softer and gentler on your skin. You are less likely to have a reaction to chlorine with a salt water pool. If you have asthma or a skin condition salt water may be better for you than other chemical systems.
- Reduces the occurrence of pool foam or scum on the pool surface.
- Chlorinators are solid state with no moving parts so very reliable and low maintenance.
- Salt water chlorination is less expensive than other sanitation solutions.
- You can use salt water in your swimming pool and spa or hot tub. There is no need to have a different sanitation routine for each pool.
- You are far less likely to get a build-up of chloramines in the pool which cause that bleach smell. Chloramines are a result of inadequate sanitation which won’t happen with salt water chlorination. So no chemical odor with salt water.
How Salty is a Salt Water Pool?
Pool salt is a purified crystallized form of common 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.
The Cost to Convert Your Pool to Salt Water
1. Salt Water Chlorinator Unit
The main cost is the salt water chlorinator unit which has to be installed after the filter. There is a controller unit which is fitted to the wall and requires electricity to run the electrolysis cell.
The cost of the average system is around $800 depending on the size of your pool.
2. Extra Power Consumption
The chlorinator cell uses a low voltage power supply to split the salt into chlorine which will add a small extra cost to your power bill which most people hardly notice. However, using a chlorinator means you don’t have to buy chlorine and some other chemicals for the pool saving you money.
3. Cell Maintenance
The chlorinator cell needs to be cleaned every 12 months by soaking it in a mild acid solution. The cell needs to be replaced every 4 to 5 years as the electrodes wear out. The cost of a new cell averages $200.
For more information please read How to Clean a Salt Water Chlorinator Cell
4. Salt
An average backyard pool requires about 10 bags of salt to convert to salt water. The last time I looked pool salt was $8 per bag.
Every year you may need to add one or two bags of salt to the pool as the chlorination process uses some salt.
Add Salt to Your Pool
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.
New Marble Plaster Pools
Most pool plaster manufacturers don’t recommend to 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.
How much salt do you put in a saltwater pool?
The level of salinity that you have in your pool depends on the chlorinator manufacturer’s specifications. Most chlorinators operate with a low salinity of 3000 to 7000 mg/l (ppm).
However, with outdoor pools in sub-tropical and tropical climates and heated pools the recommended salinity 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.
Add the Salt
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.
Use your pool brush on the long pole to push the salt around the pool to dissolve it. You will need to repeat this a few times.
Warning: Do not add salt into the skimmer box as this will clog your plumbing, increase pressure and potentially damage the filtration system.
Add Pool Stabilizer
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.
Run the Pump
Run the pool 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).
Turn On the Chlorinator
The next day ensure all the salt has fully dissolved.
Turn on the chlorinator unit to start generating chlorine.
Your Pool is Ready for Swimming
Now your poo is ready for swimming after allowing one cycle of the pump to fully dissolve and circulate the salt.
Saltwater Pool Maintenance
Pool Water Salinity
You still need to test the pool water to ensure the chemistry is right. However, you need to add one more test to the testing routine. A test for salinity of the water. I recommend purchasing the test strips for pool water salinity as they are accurate and very easy to use.
If you have added too much salt to the pool you need to drain some water and refill to reduce the salinity level. Too much salt may cause the chlorinator unit to not operate effectively leaving the water unsanitized.
If your salinity is too low add some more salt by following the supplier’s instructions.
Free Chlorine
A salt water pool must have 1 to 3 ppm of free chlorine to ensure the pool is adequately sanitized.
If the free chlorine level is too low turn up the chlorinator and run the pump longer to generate more chlorine. You can also manually add extra chlorine to increase the level.
If the free chlorine is too high reduce the pump time and/or turn down the chlorinator to produce less chlorine.
Shock the Pool
Periodically shock your salt water swimming pool just the same as a freshwater pool.
Conclusion
I recommend saltwater chlorination because I have owned a salt water inground pool for 30 years with no problems at all. Saltwater chlorination works very well and it’s inexpensive to install, operate and maintain compared to other systems.
The salt water is gentle on your skin and eyes. The salt concentration is so low that you can hardly taste the salt in the water.
What I like the most is a salt water pool virtually looks after itself on autopilot. I can go away on a holiday and the pool is sparkling clear when I return. Other sanitation options are more expensive and require more of your time to operate effectively.