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

Occasionally, stains can show up in your pool and their origin can be a mystery. 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 marks.

So how do you get rid of stains in your pool? Sometimes you need a specific pool stain remover; other times, a simple shock treatment will remove discoloration. The solution all depends on the cause of the stain. The best way to prevent and/or correct staining in your pool is with regular water testing at your local pool professional’s location.

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




Calcium based shock products, grout, mortar, plaster


Fiberglass shells




Source water, improperly balanced water and corrosion from pool equipment and excessive use of treatment algaecides




Source water, improperly balanced water and corrosion from pool equipment




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:

Treating organic stains can often be accomplished by brushing the affected area well. It may be necessary to shock your pool or use a specialty granular stain remover. Consult your local pool professional for more information about your specific issue.

There are many different types of pool finishes. Improperly applying products or using chemicals not specified for your finish could result in additional discoloration or bleaching of the pool’s surface. Be certain when using stain removal products to always follow label instructions.

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 algae growth with the appropriate treatment shock and algaecide. Check circulation and filtration systems to ensure they’re functioning properly. Be certain to add the correct amount of sanitizer, routine shock and preventative algaecide for your pool’s needs, test and balance your water weekly, regularly remove debris and brush.

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.

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: Algaecides can contain copper or silver.
  • 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 chlorine pools can be victims of metal staining. 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 local pool professional 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 removed 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 routinely add a metal inhibitor to prevent future issues.

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.

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 – and can be difficult to remove.

swimming pool tile closeup

How to remove scale:

Scale removal is best handled by a pool professional. There are many different methods to dealing with scale buildup. This can range from draining your pool and performing an “acid wash” to adding various products depending on the scope of the stain. An onsite visit by a professional is often the best track to take.

Choosing the best pool stain remover

Surface staining could be cause by a number of factors.  It’s always best to collect a water sample for testing and speak to your local pool professional about the best removal and prevention process.

Tips for identifying and treating surface stains:

  • Be able to describe the amount of staining in the pool, where it is and what color it looks like.
  • Try brushing the affected area.  Note if the discoloration lightens or decreases in size or shape.
  • Take a picture during a shadier time of day if possible.  This will give you something to show your pool pro.

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 choosing 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 problem chemicals into your pool water.
  • Be certain to always follow product label instructions.
  • 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 professional. They can effectively identify the discoloration to start the most effective removal process and offer pro tips to prevent any future staining.

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