How to Identify and Remove Pool Stains

Maintaining a clean and sparkling pool is a top priority of every pool owner. But even if you put plenty of time and effort into pool maintenance, pool stains can develop on the walls and floor.

Unfortunately, pool stains are hard to get rid of. You will need to go further than a routine cleaning to tackle them. I’ve put together a list of straightforward steps you can take to get your pool looking as good as new when you tackle stains.

What Causes Pool Stains?

The first step to removing a pool stain is identifying what caused it in the first place. You can determine the type of stain by observing its color and performing an identification test.

Types of Pool Stains

If you spot a stain in your pool, it will fall into one of two categories.

Organic Pool Stains

Organic pool stains are caused by natural materials, such as algae, berries, leaves, and other debris from the environment surrounding your pool.

Metal Pool Stains

Metal objects, such as copper and iron, can cause stains in the pool when introduced to the water. According to the Independent Pool and Spa Service Association (IPSSA), copper stains are prevalent and are often caused by algaecides or worn pool plumbing.

Iron stains are caused by the erosion of improperly installed pool heater headers, lawn fertilizers, and most commonly, the use of well water.

Pool Stain Colors

Observing the color of the stain is one of the best ways to determine what type of stain you are dealing with. Some colors indicate an organic stain, while other colors mean a metal stain that might be more difficult to remove.

  • Blue-green stains are usually indicative of copper stains, but if the surrounding pool water is cloudy and the stain is slimy in texture, a greenish color could also indicate an algae-induced organic stain.
  • Purple stains on pool tile lines and the surface of a pool appear due to an excess of copper cyanurate and are evidence of a metal pool stain.
  • Brown stains signify iron dissolution and are often indicative of iron buildup.
  • Green-brown stains are caused by leaves, dirt, and other debris surrounding the pool area and signify organic stains.
  • Red-blue stains are evidence of berry residue and are likely to appear if a berry-producing plant resides near the pool.

How to Test For Stains

While the color of a stain can often help you identify whether a stain is metal or organic, there are circumstances where it is more difficult to discern. Misdiagnosing a pool stain and treating it with the wrong materials is the last thing you want to do as a pool owner.

It is common for pool stores to immediately recommend algaecide for green pool stains. However, if the pool stain turns out to be from copper, algaecide can actually make the stain worse.

Mistaking metal marks for organic ones is an easy problem to avoid if you follow these simple tests to discern the nature of the stain you are dealing with.

How to Test For Organic Stains

If you suspect you have an organic stain on your hands, the best course of action is to apply a small, concentrated amount of chlorine to the area in question. This will eliminate an organic stain. If the stain does not disappear, you are likely dealing with a metal stain.

How to Test For Metal Stains

Since chlorine does not affect metal, you’ll have to take a different approach with metal stains. Apply a small amount of citric or ascorbic acid (vitamin C tablets) in the form of a dry powder or granules to the affected area. If this removes or at least lightens the stain, it is a metal stain.

How to Get Rid of Pool Stains

Now that you know how to identify and test for the type of stain, you’ll need to go through the steps for removing the stain. There are different methods for organic and metal stains.

How to Remove Organic Stains

Adding chlorine is not only the best way to test whether you have an organic stain, but also the most effective method for entirely removing organic stains from your pool.

According to the American Chemistry Council, when added to water, chlorine disinfectants eliminate water-borne germs found in organic materials that stain a pool, such as algae. The presence of organic stains often indicates that the “free available chlorine” or FAC level in your pool is too low.

The best way to treat an organic stained pool with chlorine is to raise the FAC levels by “shocking” the pool, which adds oxidizing chemicals to pool water and boosts chlorine levels to destroy bacteria.

Here’s an outline of the steps you can take to get rid of organic stains that discolor your pool walls:

  • Test the pool water. Test the total chlorine, the FAC level, the pH level, the pool’s alkalinity, and the calcium hardness of your pool. The Association of Pool and Spa Professionals recommends maintaining a FAC of 2.0-4.0 parts per million (ppm), a pH level of 7.2-7.8 (ideally 7.4-7.6), total alkalinity of 100 ppm, and calcium hardness of 200-400 ppm.
  • Shock the pool. Following the instructions provided on your pool shock product, super chlorinate your pool by adding ten times the total chlorine. You can achieve this by adding a higher dose than the standard pool shock treatment, which is roughly 3 pounds of calcium hypochlorite shock per 10,000 gallons of water in your pool.
  • Brush your pool. Vigorously brush the sides of the pool, wherever the stains are located. You may not be able to remove all of the stains at this time, but it will help with the process of breaking up the organic material.
  • Leave your pump and filter running. Shock treatment works best when allowed to circulate, preferably for at least eight hours.
  • Give the pool another scrub. After the pool has circulated for a while, give it another scrub. This should help remove any remaining stains on the sides of the pool.
  • Treat your pool after sunset. Shocking your pool is most effective after dusk. It prevents chlorine from losing effectiveness, which can occur with ultraviolet ray exposure during the day.

How to Remove Metal Stains

Eliminating metal stains is slightly more complicated and time-consuming than tackling organic stains, but the process is still straightforward. I recommend treating copper or iron stains with a combination of citric or ascorbic acid and a sequestering agent.

Follow these steps to treat your pool for metal stains:

  • Test the water to determine the source of the metal. As with removing organic stains, testing your water to ensure it is adequately balanced is an essential first step. Additionally, it is possible to determine which metal is causing a stain with a home test kit.
  • Apply citric or ascorbic acid granules. Using either a liquid or dry acid treatment, apply the stain remover to the pool and allow it to filter. Apply a treatment that specifically targets the type of metal you tested the pool water for, as treatments vary.
  • Add a sequestering agent. This will help your pool’s filtration system filter out the metals the acid granules lifted. Note that some sequestering agents contain phosphates that require further action to be removed. If you choose a non-phosphate sequestering agent, it is worth noting that these products typically only work on new stains that haven’t yet reached the pool’s surface.

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How to Prevent Pool Stains from Returning

One of the easiest ways to combat pool stains is to take the necessary precautions to prevent them before they occur. You can take some measures to fend off both organic and metal pool stains.

How to Prevent Organic Pool Stains

Preventing organic pool stains is a matter of regular cleaning and maintenance. The following are best practices for keeping environmental factors from contributing to stain development:

  • Keep your pool water balanced. The most effective way to prevent organic pool stains is to regularly monitor the pH, FAC, total chlorine, and alkaline levels in your pool water and adjust your treatment based on the Association of Pool and Spa Professionals’ guidelines.
  • Keep your pool clean. There are many ways you can monitor and maintain your pool’s cleanliness. Some of the best methods are to invest in an automatic pool cleaner or vacuum your pool by hand, brush your pool walls, and regularly skim your pool’s surface to prevent any debris or dirt accumulation.
  • Clear your pool of unnecessary surroundings. If your pool is surrounded by plants that shed an excessive amount of leaves, debris, or berries, consider moving them or trimming branches wherever possible.

How to Prevent Metal Pool Stains

While preventing metal pool stains requires more attention and a few additional provisions in comparison to preventing organic stains, following these guidelines will help keep metals from developing marks on your pool’s floors, walls, and surfaces.

  • Keep your pool water balanced. This is a crucial component in general pool maintenance and the primary method to prevent organic and metal pool stains. Most staining is a direct result of chemical imbalances.
  • Test your pool water for metals. Using the at-home test kits to ensure that you don’t have an excess level of metals in your pool water is an effective way to prevent staining.
  • Be aware of factors contributing to increased metal levels in your pool water. Regularly check the metallic levels in your water if you use well water to fill your pool, if you frequently apply fertilizers to your lawn, or if the plumbing of your pool system is old and worn.
  • Adopt a sequestering agent in your weekly, biweekly, or monthly pool maintenance routine. This will keep metals from gathering into splotchy stains on the pool’s surfaces.

Say Goodbye to Stains!

While displeasing to the eye, swimming pool stains are nothing to panic about. Once you conquer the algae, iron, or copper buildup, you’ll be free to swim to your heart’s content.

Following my guide will allow you to remove organic or metal-based stains efficiently.

As long as you check your pool’s pH levels frequently, adopt a regular maintenance routine, and invest in preventative pool treatment, you’ll be rid of stains for good!

Have questions? Feel free to shoot me a message.

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