I came across an online article today that shows how you can’t always believe what you read. The story suggested that a salt water pool “gets cleaned” using a “filtering system” called a salt chlorinator.
I’m guessing it was written by someone who has never owned a salt water pool. Anyone who owns a pool knows that “cleaning” a pool refers to vacuuming it, skimming it or otherwise physically removing debris from the pool.
Anything related to chlorine or chlorination refers to sanitizing the pool. That’s what kills bacteria and keeps the water crystal clear.
A salt chlorinator converts dissolved salt into chlorine using a process called electrolysis but doesn’t filter pool water in any way. All pools including salt, old style chlorine, ozone and other types require a separate filtration system on top of that to actually filter the water.
I have owned a salt water pool since 2006. Below is my experience with them along with some advice regarding how to better manage them. We’ll specifically discuss how salt chlorinators work, how pool filters work, and the differences between them.
Basically, I’ll explain how certain words are misused regarding salt water pools and at the end, I’ll also give you a tip in case you own a cartridge filtration system like I do…
What does a salt chlorination system do?
A salt chlorinator has several roles depending on which model you choose and how sophisticated its functionality. The main job of a salt chlorinator is to convert dissolved pool salt – which gets added directly to the pool water – into a natural form of chlorine using a process called electrolysis to sanitize the water.
An old style chlorine pool uses chemical liquid chlorine, crystal chlorine or chlorine tightly packed into small pucks to sanitize the water. This chlorine gives off the classic chlorine smell that we are probably all used to and is also responsible for reddening your eyes and leaving your hair, skin and swimming trunks and bikinis with the same chlorine smell.
The chlorine produced by a salt chlorinator is simply pool water combined with almost completely pure (99% plus is the best) salt that is run through your pump and into the salt cell that your chlorination has. This salt cell electrifies the dissolved salt contained in the water and converts it into a natural, odor-free form of chlorine often referred to as sodium hypochlorite i.e. liquid chlorine.
Salt is comprised of sodium and chlorine and is known as sodium chloride (NaCl). So salt naturally has chlorine occurring in it. But in a pool it requires the process of electrolysis to convert the NaCl to chlorine that will sanitize the water and kill bacteria and that’s where the salt chlorinator comes into play.
The salt chlorinators on the market today typically involve several main parts:
- Chlorinator control board: The main control board computer monitors the activity and controls the electrolysis function, enables you to set timers for your pump and chlorine production, monitors various water chemistry levels and things of that nature. It’s the brains of the operation.
- Salt cell: The salt cell is a hard plastic tube that screws directly into your existing plumbing. Inside the salt cell are titanium plates that when electrified with a charge, convert the dissolved salt into chlorine as it passes through before it goes back into the pool.
To answer the question of what other roles a salt chlorinator has, it again depends on which brand and model you choose. Some also enable you to run your pool heater, pool lights and other devices through it on schedules, perhaps even remotely.
What does a salt water pool filter do?
A filtration system in a salt water pool does the exact same thing that a filter does in any pool: It removes debris from the water to keep the water clean and free of leaves, twigs, dirt, sand and other contaminants you’d prefer not to have to swim in.
If you go back to the above section on the role of a salt chlorinator, nowhere will you see a reference to filtering or cleaning water because that’s not what it does. A pool filtration system cleans water by filtering out debris such as leaves, twigs, sand, dirt, oils, hair and even dead rodents if they unfortunately fall in.
People generally think of a pool filter as once specific thing which it is. But your pool filtration system is actually much more than that.
Your pool filtration system is typically made up of several connected and interrelated parts that all work together:
Pool filtration system
When pool owners think of their pool filter, they probably think of the large plastic (usually) container that is hooked up to piping and is stationed near the pump and other pool equipment. Depending on the style of pool filtration you purchase, it’s design and components will differ.
Regardless, its main purpose is to remove impurities from the pool water and keep it clean for swimming.
Main drain
The main drain is located at the very bottom of the pool in the deepest area. When the pump is turned on, it sucks water in and delivers it to the pump, through the filter and then returns the filtered water to the pool.
Skimmer
The skimmer is located on the side of the pool usually near the middle. It’s normally accessed by removing a plastic cover located on the ground.
In the skimmer sits a skimmer basket which collects debris such as leaves, twigs and things of that nature. Like the main drain, it sucks water in too, through the pump and filter. But as the name would suggest, it skims water off the top of the pool to remove surface debris.
So while the main drain sucks water from the very bottom of the pool, the skimmer draws it from the very top to remove objects floating on the top.
Pump
The pool pumps sucks water in from the main drain and skimmer, first running it through its basket to remove large debris such as leaves and twigs that may have somehow made its way through either the main drain or skimmer. Water then gets pushed into the filter for filtration before the water is returned to the pool.
When the pool pump is shut off, filtration does not occur nor does the production of chlorine through the salt chlorinator.
What kind of filtration system does a salt water pool use?
Salt water pools can use the exact same filtration systems that other pools use. The three main kinds of pool filters are sand filters, cartridge filters and Diatomaceous Earth (D.E.) filter.
In fact, if you have a regular chlorinated pool and convert it to a salt system, you don’t have to change the filtration system and can keep using it. It’s that simple.
Check out my article called Best Salt Water Filter For Pools (3 Types) to learn more about each main type of pool filter. All can be used with a salt water chlorination system.
In terms of cost and how effective they are at removing contaminants from the water:
- Sand filters are the cheapest and least efficient
- Cartridge filter are more expensive and better than sand filters and can remove smaller particles
- D.E. filters are the most expensive and are the best at removing more and smaller particles.
Summary
A salt water chlorinator produces chlorine from dissolved salt through a process called electrolysis. The chlorinator does not clean or filter the water in the way that pool owners typically use those words.
Cleaning a pool typically refers to vacuuming or skimming the pool to manually remove debris.
A pool filtration system is used to actually filter the water. It’s completely separate from the chlorinator but is connected to the same piping so they function together. They just do different jobs!
Last tip: If you own a cartridge filtration system like I do, the unit itself is the filter. The round pleated drums inside the filter are actually the cartridges. So when you call your pool company because you need to replace your cartridges, use that word instead of filter! You don’t want them to quote you on a filter replacement because that’s the entire system. You just want to replace the cartridges.