Ascrobic & Citric Acid Stain Removers

Ascorbic & Citric Acid Pool Stain Removers - Worth It?

Citric acid and ascorbic acid are both acids that are commonly used in the pool stain removal process. Some pool owners swear by their effectiveness, but are they actually worth using?

In this article, we will discuss what ascorbic and citric acid stain removers are, how they work, and when to use them. We also include a step-by-step guide for how to use these stain removers in your pool!

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What Are Ascorbic Acid & Citric Acid Stain Removers?

Citric acid and ascorbic acid pool stain removers are products that work to remove specific types of stains from the lining of your pool.

Both of these acids act as reducing agents, which remove stains from your pool by lifting the stain-causing, metal particles from surfaces and turning them into colourless, soluble ions.

While ascorbic acid is great at removing iron stains, citric acid pool stain removers work best at removing copper. You may also read about vitamin C as a pool stain remover. Vitamin C is the same thing as ascorbic acid, making it the most effective on iron and rust stains.

Citric acid and ascorbic acid differ slightly in their pH. Citric acid has a pH of around 4.5, while ascorbic acid tends to fall around 2.5, making it a much stronger acid.

How To Use Ascorbic Acid & Citric Acid Stain Removers

Diagnose Your Stain

The best way to diagnose stains is to get your pool’s water tested for dissolved metals. This can be done using at-home test kits, but is perhaps best done by taking a water sample to your nearest pool supply store that performs water metal testing.

At home test kits can be effective, but these often require you to test for one type of metal at a time, which would require that you purchase many different test kits.

Choose A Product

If you have iron stains in your pool, choose a vitamin C pool stain remover composed of ascorbic acid. While using crushed vitamin C itself can be a great spot treatment, much more ascorbic acid will be needed to treat an entire pool. This can be purchased in bulk in a granulated formula.

If you have copper stains in your pool, use a citric acid stain remover. Citric acid is commonly found in many stain removal products or can be purchased in bulk on its own.

We recommend using stain removers that contain these acids rather than the acids directly, as these products are often balanced for pool use and may have other features such as sequestering agents and clarifying compounds.

Before Treating Your Pool

Before treating your stains, consider lowering the pH of your pool using hydrochloric acid or dry acid. Many stain removal products benefit from temporarily lowering the pH of your pool below 7.2 as these chemicals are more effective in acidic waters.

You should also gather supplies, such as a mixing bucket and protective eyewear.

Using The Stain Remover

Measure out an adequate dose of stain remover for your volume of pool, then dissolve the stain remover in a bucket of pool water. Mixing is not always required for these products; check your product’s instructions to see if this is applicable to you.

With the pump shut off, distribute the stain remover around your pool. You may also opt to add extra product near concentrated areas of staining instead if you are seeking more of a spot-treatment.

After Removing Stains

After letting your stain remover work its magic for 2-3 days, you can turn your pump and filter back on and rebalance your pool’s chemistry.

If you lowered your pool’s pH before treating stains, be sure to raise it and your total alkalinity back within the appropriate range to avoid corrosion in your pool and discomfort for swimmers.

Many stain removal products have a depleting effect on the chlorine in your pool. Always test your pool’s free chlorine after using a stain remover to see if additional sanitiser needs to be added.

If you have high amounts of dissolved metals in your water, you may want to use a stain prevention agent after the treatment process to keep stains from forming again in the future.


Ascorbic acid and citric acid stain removers are effective products that work to remove certain types of metal stains from the surfaces of your pool. While these acids can be used on their own for stain removal, as is commonly done for the spot-treatment of stains, they are also powerful ingredients in all-over stain removal agents.

Do you have any questions about ascorbic acid or citric acid based pool stain removal? Get in touch with us in the comments, we would love to help out!

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.