Stain Identification & How to Remove Them

Warning: If you are a liner pool, be careful to not bleach or fade the liner!

How to test for which type of pool stain you have:

Testing the stain to see if it’s Organic
1. Add a few sprinkles of granular chlorine directly to the stain
2. Scrub the chlorine granules into the stain with a brush
3. If the stain begins to fade away, it’s organic
4. If the stain doesn’t fade away, it’s likely metal

Testing the stain to see if it’s Metal
1. Add about a handful of ascorbic acid (or crushed Vitamin C) directly to the stain
2. Scrub the ascorbic acid into the stain
3. If the stain begins to fade away, it’s metal
(This may also work on rust stains too)

Testing the stain to see if it’s Rust
1. Add about a handful of dry acid (sodium bisulfate) directly to the stain
2. Brush the dry acid into the stain
3. If the stain begins to fade away, it’s rust

removing Organic stains:

Good news: Of all pool stains, organic pool stains are the easiest to remove

That said, you’ll still need to use a little elbow grease to get rid of them. Luckily, whether you’re trying to remove leaf stains or algae stains from your pool, there’s a simple method to follow.

You can remove most organic pool stains by:

  1. Shocking your pool
  2. Applying granular chlorine to the stain (If you have a liner, be careful not to bleach it!)
  3. Allowing the chemicals to absorb
  4. Scrubbing the stained area

Simple enough, yes, but it can be improved.

For the most effective organic pool stain removal, follow these steps:

  1. Test and balance your pool’s pH and alkalinity levels
    • Proper pH is between 7.4-7.6, and alkalinity between 100-150
    • Balancing these chemicals will make the soon-to-be-added chlorine way more effective
  2. Use at least 2 pounds of calcium hypochlorite pool shock to super shock your water
    • 1 bag per 5-gallon bucket of water. Gradually mix the shock into the water bucket.
    • Shock at dusk or night to avoid chemical depletion from the sun
  3. Wait a few hours for the shock to circulate
  4. Apply 1-2 cups of granular chlorine to the stain
  5. Scrub the granular chlorine into the stain
    • If the brush doesn’t work, try using a soft tile grout scrubber
  6. Continue scrubbing and applying granular chlorine until the stain is gone

For especially tough organic stains use an enzyme treatment. They can be purchased at any pool store, and help break down organic matter that’s too tough for just chlorine.

Removing metal pool stains: 

Metal pools stains are a bit trickier. They only respond to certain chemicals, so chemicals like chlorine don’t make a dent.

But there are chemicals that do.

  • Removing iron pool stains
    • Ascorbic acid is found in most stain and scale products and works great for removing iron-based stains.
  • Removing copper pool stains
    • Citric acid works similar to ascorbic acid but is more effective at treating copper based stains.

If you aren’t sure what type of metal you’re dealing with, you can bring a water sample to your local pool store for testing, or purchase a pool metal test kit.

For the most effective metal pool stain removal, follow these steps:

  1. Deactivate excess metals with a metal reducer (like Metal Free or Rust N Scale)
  2. Add a 1/2 pound of ascorbic acid per 10,000 gallons or water
  3. For tough stains, sprinkle ascorbic or citric acid directly onto the spot
  4. Scrub the stains
  5. Run your filter for  at least 1 hour
  6. Repeat steps 2-4 until stain gone
  7. To finish, add a metal eliminator pack to your skimmer basket to prevent future buildup


Removing rust pool stains:

Rust isn’t as bad to deal with as the other stains. And sometimes, it can even be treated with some of the same methods used for organic and metal stains.

But if you want to remove a rust pool stain fast, follow these steps:

  1. Fill up a sock with around a 1/2 cup of dry acid
  2. Place the dry acid filled sock over the stain (Again, if you have a liner, be careful not to bleach/fade it!)
  3. Use a pole or weight to keep the sock pressed against the rust
  4. Check the sock every 1-2 minutes
  5. If the stain is still there, continue “soaking” it with the sock
  6. Scrubbing the stain with ascorbic or citric acid can speed up the process
  7. Remove the sock as soon as the stain is gone to avoid a discolored spot

This also works if you’re trying to get rust stains off the bottom of the pool. Simply use a telescopic pole to apply the dry acid sock to the stain.

Removing waterline pool stains:

If you look at your pool’s water line and see a white-pinkish colored residue, this section is for you.

Most water line stains are naturally caused over time by a buildup of organic matter like dirt and bodily oils.

To remove pool waterline stains:

  1. Add an enzyme treatment to your pool
  2. Brush the waterline stains with sprinkles of granular chlorine
  3. Use a brush or pool stain eraser for hard stains 


Removing mineral pool stains:

Similar to waterline stains, mineral stains are the scaly chalk white deposits that tend to form right above your water line. They’re usually caused by excess calcium in the water.

There are few ways to remove mineral stains, which include:

  • Mixing a 50/50 vinegar-water solution and using it to scrub out the stain
  • Baking soda and vinegar mixture plus scrubbing
  • Lime juice and salt plus scrubbing 


How to prevent swimming pool stains:

So what’s the one surefire way to prevent pool stain?

Bulletproof pool maintenance habits.

What do we mean by that?

Well, we don’t expect you to brush your pool 24/7 or anything crazy like that. Instead, just a few changes that’ll keep your pool clean and fend off buildup. A defense against future pool stains.

To prevent pool stains from returning in the future:

  • Test and balance your water at least twice a week
  • Keep your pool properly sanitized (3 ppm)
  • Skim and brush the pool 2-3 times each week
  • Vacuum at the end of each week for a spotless and debris free floor
  • Add a mineral sequestering agent to lock up excess minerals
  • Add a metal eliminator to contain and deactivate excess metals