How to Identify and Remove Pool Stains Common Sources of Stain Organic Stains Metal and Mineral Stains Scale Deposits Choosing the best stain remover Recommended Brands

How to Identify and Remove Pool Stains

Every swimming pool owner knows that pool stain removal comes with the territory. But stains in your pool are not necessarily an indication that your pool water is dirty. Keeping your pool water clean is just one part of getting rid of stains in your pool. Sometimes you can scrub and scrub and still see streaks.

So how do you get rid of stains in your pool? Sometimes you need pool liner stain remover; other times, a simple shock treatment will remove discoloration. The solution all depends on the cause of the stain.

Common Sources of Pool Stains

Improperly balanced water is the root cause of many pool stains. If your pH levels are off, discoloration, scaling, and staining are soon to follow. There are several culprits to your pool stains. The first thing you need to do is figure out whether yours are organic, metallic or scale stains. Use the chart below to uncover your stain’s source:

Organic Stains




Leaves, acorns, mud, animals, berries




Improper water balance

Metal and Mineral Stains




Chlorine shock, grout, mortar, plaster




Fiberglass shells




Algaecides, ionizers, pipe corrosion, fittings, heaters




Well water, pipe/pipe fitting corrosion




Well water

Scale Stains




Hard water, high pH /alkalinity / calcium levels, temperature fluctuation, pool water evaporation

Organic Pool Stains

A greenish-brown stain is commonly caused by leaves, acorns, mud, or worms (or other animals) in the bottom of the pool. Red or blue stains are often the result of berries. Green discoloration can also be the result of an algae bloom.

swimming pool with puppy swimming

How to remove pool stains from debris:

To treat organic stains, you must first expose the stain to the air, in order to apply the treatment. You can do this by lowering your pool water level, or in severe cases, draining the pool if the stains are towards the bottom of your pool. The type of treatment will depend on personal preference and the material of your pool walls.

Chlorine granules, a diluted solution of muriatic acid, or a less harsh cleanser can be applied directly to the wall. Some stains will respond to vitamin C in a natural ascorbic acid-based or diphosphonic acid-based pool stain remover, although these might require a bit more elbow grease.

The material of your pool walls and floor dictates the application method. Fiberglass pool stain remover and plaster pool stain remover differs from concrete pool stain remover. For example, concrete pool stains can be removed by sprinkling chlorine granules over the affected area to bleach out the discoloration, while the treatment for vinyl pools should be pre-dissolved and poured directly over the stain.

To prevent future organic pool stains, stick to a routine pool cleaning and vacuuming schedule. Some pool owners find that an automatic pool cleaner takes the hassle out of the process. Keep foliage out of the pool by making sure to trim trees and bushes around the pool and using a strong pool cover when the pool is not in use.

How to remove pool stains from algae:

Keep in mind that if a green discoloration brushes off or dissipates with a shock treatment, you don’t have stains – you have algae. Kill off algae blooms with granular chlorine, pool algaecide, or chlorine pool shock. Then be sure to have your water balance, circulation, sanitation, and filtration systems checked to keep them functioning properly and efficiently, and regularly have your pool vacuumed and brushed.

Metal and Mineral Pool Stains

If it’s not from organic materials, you’re most likely looking at a metallic stain. Metals and minerals often find their way into your pool water. Your pool components themselves contain many metallic parts, from the heat exchangers to the brass gate valves to the copper or galvanized plumbing fixtures. If your source water comes from a well, you can be sure that minerals – like copper, iron, manganese, and magnesium, not to mention any additives used to sanitize the water supply – will appear in your pool.

Common Sources of Metals and Minerals in Your Pool

  • Metallic Equipment: Heat exchangers, gate valves, and plumbing fixtures are typically brass, copper, or galvanized iron or steel.
  • Well Water: Well water often contains copper, iron, manganese, and magnesium. Municipalities often use several metals/minerals to sanitize the water supply.
  • Pool Chemicals: Many algaecides are copper- and silver-based, and salt contains trace amounts of iron.
  • Lawn Chemicals: Fertilizers and pesticides for lawns, golf courses, and pond/lake shorelines contain metals. (Even if it’s not on your property, these chemicals can become airborne and settle on your deck or in your pool water.)

Both traditional chlorine pools and saltwater pools can be victims of metal staining. Many algaecides used to keep chlorinated water clean are metal-based, usually containing copper and silver, while the chlorine itself can contain trace amounts of iron. The salt used in chlorine generators for saltwater pools also contains iron. All these metals leach into the water over time, discoloring your water and eventually staining your pool finish.

They’re unsightly, sure, but rest assured that most metal-based discoloration is purely aesthetic. Your finish will not be damaged if you leave it untreated.

inground swimming pool

How to remove metal pool stains:

Determine the source of your stain first to figure out how best to mitigate it. You can either use a home test kit or collect a sample of your pool water and take it to your pool retailer for testing. Then you’ll know which type of pool metal stain remover will best target your culprit(s). Each pool stain remover and or neutralizing chemical works differently, so pay close attention to the manufacturer’s instructions.

Once you’ve cleaned away all the mineral and metal stains, be sure to maintain water balance by using a good water chemical testing kit. If you see severe or recurring metallic pool stains, add a metal eliminator to your water pump basket to absorb excess metals from your pool water.

Scale Deposits on Your Pool Walls

Waterline scale is very common, especially if you have hard water. This generally appears as a whitish crust along your swimming pool wall, but if it sits for long, it can turn brown or grey as the calcium pulls in dirt and oil.

Calcium scale deposits are often a sign that the pH, alkalinity, or calcium levels in your pool water are too high. Constant fluctuations in temperature and rapid evaporation will also cause these deposits to form on the side your pool. Iron scale can also form on your pool’s metal surfaces, surrounding or covering the surfaces of things like ladders, lighting, drains, and other plumbing elements as calcium reacts with the iron in the pool.

Scale deposits should be removed as soon as you notice them. Scale has a rough texture that gets worse if you don’t treat it because it builds up on itself. It can cause permanent damage to your pool’s surface.

swimming pool tile closeup

How to remove scale:

Use a calcium scale remover to take care of those deposits. The deposits can also be scraped off with a blunt tool, like a flathead screwdriver or a putty knife. Then polish up the area: Fill a spray bottle with equal parts water and acid. Spray on just enough diluted solution, finish the area, then rinse. For a more detailed guide to pool tile maintenance, see our guide.

For excessive scale build-up that you can’t handle yourself, your pool retailer can point you to a local company specializing in bead-blasting for scale removal. But remember, if you don’t check and adjust your pH and calcium levels in your water, you’ll face this recurring discoloration.

Choosing the best pool stain remover

A common question for many pool owners is, what is the best pool stain remover? There are a plethora of options on the market today. You’ll have plenty to choose from, and much of your decision should revolve around the type of pool liner you have and the type of stain you’re facing.

When choose a stain remover, remember some key guidelines to protect yourself and your pool:

  • Be sure to select an agent that specifically targets your culprit. You’ll waste time and money if the product attacks calcium scale when you’re dealing with organic discoloration.
  • Choose pool-specific cleansers. Never use household cleaners because they can introduce phosphates and other new problem chemicals into your pool water.
  • Be sure to follow all directions and manufacturer recommendations. Always wear gloves and goggles when working with cleaners in your pool, and be especially careful to rinse off the cleaning agent quickly and thoroughly.
  • Keep in mind that some discoloration is not a stain at all, simply the mottling of the plaster. Because it’s a natural product, subject to variations in hue, some shading or streaks can’t be removed.

If you’re not seeing results, reach out to your local pool retailer. They can effectively identify the discoloration to start the most effective removal process and offer pro tips to prevent any future staining.

Recommended Brands

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