How to Remove Algae from a Salt Water Pool

If you’ve ever woken up to a discolored saltwater pool, then you know how quickly algae can overtake your pool. One day you’re splashing around in clear water, and the next, your swimming pool is out of commission.

In most cases, removing algae from your saltwater pool is a DIY task, though some types of algae will be harder to get rid of than others. However, if you regularly maintain your pool, you should already have most of the tools you will need for the job on hand.

It may take some time and effort to eliminate the aquatic invader, but it’s doable and can save you the expense of hiring professionals. Plus, next time you see a hint of algae in your pool, you will know how to treat it immediately to avoid having a bigger problem on your hands down the line.

What Causes Algae in a Salt Water Pool?

Two things need to happen simultaneously for algae to contaminate your saltwater pool:

  • Your pool has to become chemically imbalanced.
  • Algae spores have to enter your pool.

Prevent just one of these, and you can avoid a pool algae infestation. And here is a little industry secret: keeping your pool water balanced is much easier than trying to keep algae spores out.

The Role Your Salt Chlorine Generator Plays in Algae Prevention

A salt chlorine generator is your friend in the fight against algae contamination. It converts the salt you add to your pool into chlorine via an electric current that zaps the pool water as it passes through the machine. By comparison, in a standard pool, chlorine is added directly to the pool water.

Regardless of pool type, once the chlorine hits the pool water, it is converted to hypochlorous acid, which is the stuff that fights the algae, bacteria, germs, and other unwanted aquatic invaders.

In a saltwater pool, chlorine is released at a slower rate than in a chlorinated pool, which means that the chances of algae taking root are much higher. To make sure that your pool stays balanced, test your pool water at least several times a week. There is no such thing as over-testing, though, so if you want to check more frequently, you can!

When you test and balance your saltwater pool, you need to make sure that the amount of hypochlorous acid – the stuff that kills algae – is just right; otherwise, your pool water will be too acidic or not acidic enough. You need to be sure that the other chemicals in your pool are also properly balanced.

The salt chlorine generator makes it easier to balance your pool water and will warn you if your salt levels are out of range. However, make sure that you know the right balance of chemicals for your pool water. This will vary by the pool but will typically fall in the following ranges:

  • Salt levels: 2,700-3,500, but will depend on your salt chlorine generator
  • Free chlorine: 1-4 PPM
  • pH: 7.2-7.6
  • Alkalinity: 125 is the sweet spot, but anywhere between 80-150 PPM will do
  • Calcium hardness: 200-275

Types of Algae That Can Invade a Salt Water Pool

There is a myriad of ways that algae spores can enter your pool, including:

  • On your bathing suit, pool toys, pool cleaning tools, etc.
  • Wind can blow spores into your pool.
  • Heavy rains can wash spores into your pool.
  • Direct sunlight can break down chlorine faster, leading to algae overgrowth.
  • High temperatures can accelerate the growth of algae once it is in your pool.

Several different types of algae can set up shop in your pool. The type of algae will determine how difficult it will be to remove.

Green Algae

Green algae are the most commonly seen algae in pools and grow very quickly. If you’ve experienced your pool changing colors seemingly overnight, it was likely due to green algae contamination. Green algae also generate energy and feed off of sunlight. That is why algae contamination can get out of hand quickly on sunny days.

Green algae usually look slimy and tend to cling to surfaces. Here’s a photo of what it looks like in a very dirty salt water pool.

The good news is that while green algae may take over rapidly, it is the easiest to remove. To clear your green pool, you will probably need to shock your pool twice. Check out my guide on how to shock your pool if you don’t know the proper steps.

Yellow Algae

Yellow algae, or mustard algae, usually grow slower than green algae. Unlike green algae, it grows best in shady spots and still water. It typically looks dry or powdery, so initially, you may mistake it for dirt, pollen, or sand on the bottom or sides of your pool.

Yellow algae contamination can also resemble a stain or a blob at the beginning. So, overall, not a good look for your pool.

Yellow algae are resistant to chlorine, so it is also more difficult to remove than green algae. You may have to shock your pool three times to get your yellow algae contamination under control fully.

Black Algae

Black algae look like mold and may start as a few black spots that eventually can grow into clumps. Black algae tend to grow more readily on porous surfaces, so it is less likely to contaminate fiberglass or vinyl-lined pools. Black algae can make you sick, so do not swim in a pool that appears to be contaminated.

Black algae are more resistant to chlorine than green or yellow algae and are the hardest to eliminate. You may have to quadruple shock your pool water to put an end to the contamination.

Pink Slime

Pink slime is actually a bacteria, though sometimes people refer to it as algae. Like algae, pink slime is another commonly occurring problem in pools. Pink slime may look like sludgy or mucousy streaks. It is not sanitary, and you should avoid the pool until the contamination is under control.

Pink slime is just as stubborn as black algae. You may need to shock your pool three or four times to fully remove the bacteria.

Step-By-Step Process for Removing Algae From Your Salt Water Pool

Ensure that you have all of the tools you will need to clean up your saltwater pool on hand before you start. You will need the following:

Once you have gathered your materials, you are ready to return your pool to a sparkly clear condition in fewer than ten steps.

  1. Test and rebalance your pool water using your pool water test kit.
  2. Apply a pool shock per the container’s instructions.
  3. Scrub the pool’s surfaces – the bottom of the pool and sides – with an algae brush. If your pool has a vinyl lining, you can use a regular brush.
  4. Apply an algaecide per the instructions on the container.
  5. Leave the treated pool water to circulate for approximately 24 hours.
  6. Scrub the pool’s surfaces – bottom and sides – with an algae brush again.
  7. Vacuum up the loosened algae in your pool. You will likely need to add water to refill your pool after this.
  8. Test pool water and balance it again.
  9. Make sure your pool filters are clear of any algae residue.
  10. Your pool is ready to be enjoyed!

Tips for Preventing Algae from Returning in Your Salt Water Pool

You may have heard that an ounce of prevention is worth a pound of cure. While usually applied to medical problems, this also holds true for pool maintenance.

Keep your pool clean and well-balanced to avoid a full-on algae contamination. If your pool water starts becoming cloudy or you see discolored spots in the water, you are entering dangerous territory. Treat your water immediately.

Some other steps you can take to prevent algae from coming back in your saltwater pool include:

  • Get a pool cover, though keep in mind that salt water may damage parts of the cover, depending on the type you have.
  • Test your pool water daily or get a smart water monitor to do the testing for you.
  • Don’t rely solely on your water filter to clear the pool. You can proactively vacuum your pool to get rid of any potential build-up before it gets too far out of hand.

Get My Free Pool Care Checklist

Download my free, printable pool maintenance checklist to help you accomplish regular pool care tasks for any type of swimming pool.

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Final Thoughts

With these few observations and methods, you’ll have a clean, algae-free pool in fewer than ten easy-to-follow steps. Removing algae from your saltwater pool is as easy as preventative maintenance. Avoiding an algae infestation is even easier. Once you know why algae grow in pools and what to do to prevent it, you should not have to fight another full-blown contamination again.

Your pool is ready to be enjoyed once you have completely cleared the algae and your pool water balance is restored. Though most algae are not harmful, try to avoid swimming in pools with algae or slime build-up, as some types can make you sick.

If you have any questions, don’t hesitate to shoot me a message.

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