The salt in a salt water pool is often a misunderstood aspect of pool chemistry and people often don’t know exactly what it does and doesn’t do.
Salt is added to a pool only if it has a salt chlorination generator. Dissolved salt is converted to chlorine to sanitize the water when it runs through a salt cell which is part of the chlorinator. This is as opposed to manually adding chemical chlorine to a pool.
Here are a few facts about salt water pools that are worth remembering:
- An algae bloom is killed most effectively with a chemical algaecide product in any pool.
- Algae can grow in a pool when an algae bloom is present and there is a chemical imbalance in the water.
- Salt will not kill a large algae outbreak and neither will chlorine on its own.
- Dissolved salt is converted to chlorine through electrolysis to kill pool bacteria.
- A salt water pool is still a chlorine pool with other chemicals also required.
Here a few more interesting and important questions about salt water pools and answers to each.
Will salt kill algae in a pool on its own?
No, salt doesn’t kill algae or anything for that matter. Salt is added only to a pool that has a salt water chlorinator which is a system that converts the dissolved salt in the water to chlorine through a process called electrolysis.
So salt creates the chlorine that will help prevent algae but that’s as part of the greater salt water chlorination system that your pool must have. Salt on its own does not kill algae per se.
Algae grows in your pool – algae can grow in any pool – when the level of chlorine drops below the required amount or when there is no chlorine present at all, and when algae is present.
Maintaining balanced water is the way that you prevent algae from growing in your pool. At the first sign of algae, you should immediately test the water and pay particular attention to your level of chlorine as that’s where the problem will undoubtedly lie, in my personal experience.
Once you get an algae bloom or green water, you’re most likely going to have to quickly use an algaecide chemical product to get rid of it while also raising the chlorine level.
What causes algae in a salt water pool?
Algae occurs in a salt water pool for the same two reasons that it does in other pools:
- Algae blooms have made their way into the pool water.
- Your pool water is not balanced properly and most likely has a low level of chlorine.
So if you can prevent one or both of these concerns, you will avoid algae. You might then wonder how algae gets into your pool in the first place, right?
Unfortunately, algae can enter your pool water from a variety of ways that we simply can’t prevent. Algae enters the pool from rain, dirt and wind but also from contaminated pool equipment or even clothing. Poor water circulation can also cause algae to spread faster.
Also unfortunately, there are also different kinds of algae – green, yellow, black and pink – and depending on which one you get can determine how you deal with it.
The good news from personal experience is that green algae is the one you’re likely to deal with so let’s focus on that one. You can click on the links above to learn more about each.
Do salt water pools get less algae?
Not necessarily. Salt water pools are more likely to get green algae than regularly chlorinated pools. In a regularly chlorinated pools, you are typically adding large amounts of chlorine to the pool on a regular basis whether in liquid, crystal or tablet form.
These pool owners are typically also used to shocking the pool which refers to adding a large amount (or a highly concentrated amount) of chlorine in the pool to quickly raise the level of chlorine level. This helps to ward off algae.
A salt water pool relies on the chlorinator to automatically produce chlorine and we assume that it’s doing its job, in between the water tests that we do. There is really no active participation on our part i.e. we’re not actively adding chlorine to the water. We assume it’s functioning properly.
But salt water chlorination systems are only good at maintaining chlorine levels as required and produce it at a consistent and slow rate. This is why salt water pool owners are required to add chemical chlorine into the water at pool opening each spring:
You need to shock the water with a high level of chlorine to kill bacteria that has grown over the winter.
Once the chemical chlorine has raised your chlorine level to a reasonable degree, the chlorinator can take over and maintain the required range.
But if your chlorinator stops functioning or some other problem occurs that you’re not immediately aware of, it may take several days but you will soon notice cloudy water and algae beginning to set in.
If your chlorine level has dropped to 0 or close to it, it can again be difficult and too taxing on the chlorinator to expect it to raise the level back to the required range, on its own.
At that point you’re probably going to need to use both an algaecide to get rid of the algae and a chemical chlorine shock product to quickly raise the level of chlorine.
What kills algae in pool naturally?
There are several ways you can keep algae at bay naturally although we have to stretch the definition a bit. At the end of the day, chlorinated pools use chemicals too so the word natural is used with that proviso in mind.
To keep algae from forming in your pool without extra chemical usage over and above what you normally use, do the following:
- Keep your water balanced – Maintaining water balance refers to keeping all the aspects of salt water pool chemistry inline. By doing so, you minimize the chance you’ll have various problems with your pool water, algae being just one of them.
- Pay careful attention to your chlorine levels – Specifically keeping an eye on chlorine and ensuring it remains between 1 part per million (ppm) and 3 ppm will keep algae at bay. When chlorine falls below this level or isn’t even present, it encourages the growth of green algae typically on the walls, floor and steps of your pool. Use test strips to quickly and easily measure your free chlorine level at least weekly.
- Brush the walls and floor of your pool at least weekly – You might be surprised at what grows on the liner of your pool especially if it’s a darker color which more easily hides it. We have a medium blue liner and when I brush the liner walls with the telescopic brush, I can see debris pooling up on the brush and suddenly floating in the water that I hadn’t previously seen.
Summary
In my experience as a salt water pool owner, green algae is the type that you will experience the most. Also in my experience, it’s due mostly because your chlorine level drops too low or there is no chlorine present at all, which normally indicates a problem with water chemistry or perhaps with your chlorinator.
And also in my experience, you need to address the problem(s) you’re having as quickly as possible because algae grows very quickly and noticeably. You can’t rely on the salt in your pool to fix the algae problem because that’s not what salt does.
If you have a full algae bloom – your pool water is green – you’re going to need to use a chemical algaecide product – and perhaps more than once – along with a great deal of vacuuming of the pool water to clean it up and get rid of it. You’ll be frequently backwashing or rinsing your filter and filter mediums too, trust me.
Don’t expect that dumping large amounts of chlorine in your water will quickly fix a bad algae problem either. While getting your chlorine level in the 1 ppm – 3 ppm range as quickly as possible is important, you may also need to use a chemical algaecide to get rid of the problem. Even then it may take several days.
Since the pool season is relatively short for many of us, the quicker you can get your pool water crystal clear again, the better.