A saltwater pool has a chlorination system to create chlorine using electrolysis. It converts dissolved sodium chloride that is at least 95% pure to sanitize the water rather than manually adding chlorine. A pool requires a salt chlorinator to convert salt to chlorine and cannot exist without one.
Let’s take a closer look at how a salt chlorination system is used in a saltwater pool to clean the pool water in place of regular chemical chlorine and why you might consider one for your pool.
Can I add salt to my pool without a saltwater system?
You cannot simply add salt to a regular pool and receive any benefits. A salt water pool utilizes a device known as a salt chlorinator that is effectively made up of several key parts:
Salt chlorinator control unit
This is typically a box that houses the guts of the system. It’s the computer that controls the functions of the salt chlorination system and enables it to operate. It is installed next to your pool equipment (pump, heater, piping) and depending on which model you choose can automate many aspects of pool management to make your life as a pool owner easier.
The salt cell is a tubular hard plastic device that screws into the existing pool piping (see picture below). It has a series of electrified metal plates inside but is hollow otherwise so that water is able to flow through when the pump is running.
When the chlorinator and pump are running together, the salt in the water is converted into liquid chlorine through a process called electrolysis. When the pump is running but the chlorinator is off, salt water runs through as normal after filtration and returns to the pool for swimming but no chlorine is produced.
Chlorine is only produced when both the chlorinator and pump are running simultaneously.
Water flow sensor
Installed inside the piping, the water flow sensor monitors water flow to ensure that there is always a steady flow running through the salt cell while the pump is running. The salt cell needs to be consistently immersed in water when operational otherwise it can be damaged. If water flow drops below a certain level because of a blockage, air leak or some other problem, the sensor alerts the system and shuts down the chlorinator until the correct water flow has been restored.
Your chosen brand and model might have different parts but those are the three main parts that make up the system that are required to convert dissolved salt into liquid chlorine.
Do you have to add salt to a saltwater pool?
Salt needs to be manually added to a saltwater pool by the pool owner or by your pool company. A brand new pool or one that has been emptied and now refilled (ie. the pool liner was replaced, repairs were done on the pool floor) typically requires 200 lbs of salt for every 10,000 gallons of water.
Moving forward an operational saltwater pool generally only requires the addition of a smaller amount of salt each season. In my experience, I add 130 lbs – 180 lbs (about 60 kg – 80 kg) of salt to the pool water each season. I can buy a bag of salt for under $10 and the total salt cost is perhaps $40 or so each year.
Salt doesn’t evaporate or expire but it does need to be replaced each season for several reasons. If you use a sand filter, you will need to add more salt each year than a pool with a cartridge filtration system due to water loss from backwashing.
How to add salt to a saltwater pool
Salt is manually added to the pool by dumping a bag(s) of crystalized pool salt or water softener pellets into the deep end of the pool. Salt should be poured directly into the pool and not into the skimmer. Salt levels should generally be between 2,700 ppm and 3,400 ppm with 3,200 ppm being a target to aim for. Parts per million (ppm) is the unit of measurement for salt in your pool.
Pouring salt in the deep end is ideal as it will dissolve, get sucked in the main drain by the pump and get sent through the chlorinator to be converted to chlorine. Ensure the pool pump is running to more quickly dissolve the distribute the salt throughout the pool.
It’s easier to raise the salt level in a pool than it is to lower it so if you’re low on salt and need to add some in, start conservatively and don’t add in too much. It can take a day or so for the salt level to reach its correct level as the salt dissolves. If salt levels are still low, you can add some more.
If your salt chlorinator has a live salt level reader, use that to determine when you need to add salt. You can also use salt water pool test strips or take a water sample to your pool company to get a correct salt level reading before adding salt.
What happens when you put too much salt in a pool?
The only way to lower the salt level in your pool when it’s too high is to:
- Drain some water and then refill it with clean unsalted water ie. water from your garden hose.
- Wait for the salt level to naturally go down through splashing, filter backwashing, etc.
- Wait for a heavy rainfall to dilute the pool water.
If your salt level is slightly above the desired range of 3,400 ppm and your chlorinator isn’t giving you a “high salt” warning, you might choose to do nothing and wait it out because salt level does drop over time with regular pool usage and as evaporated pool water is replaced.
How long after putting salt in the pool can you swim?
A bag of salt pellets can take up to 24 hours to fully dissolve. Pool salt that is crystalized will usually dissolve quicker since it’s already in crystal form. If you add salt in the evening after you’re done swimming for the day, you can swim the next morning as usual with no trouble.
Having said that, a general rule (unless a chemical manufacturer says otherwise) is to wait 20 minutes to 1 hour to swim after adding a chemical to the pool with the pump running. Since salt isn’t a chemical per se, it isn’t as big a concern.
But if you want to be safe and don’t want to swim in potentially highly salted water as the fresh salt is running through the pump, add salt the night before and leave the pump running over night.