How To Remove Yellow Stains From A Pool Liner – Complete Guide

Have you noticed yellow stains on your liner, and more exactly a yellow coloration of your water line? How to avoid these spots? How to get rid of it?

The water line of a swimming pool is a very sensitive area (especially when it is equipped with a liner). This is where most of the pollution is concentrated, resulting in a brown or yellow coloration of the water line.

The fouling of the water line of the swimming pool is slow and regular. It is caused by fatty substances floating on the surface of the swimming pool, including, in particular: the fallout from the combustion of hydrocarbons (chimneys, proximity to a road or an airport, etc.), body oils and pollution linked to the plant environment.

It is frequently observed that the water line is more easily marked on the sides of the swimming pool, exposed to the sun . In fact, the pollution of the membrane is activated or aggravated by solar radiation.

A yellowish coloration on the water line of your swimming pool may appear.

This coloring results from an undesirable chemical reaction between certain anti-UV agents incorporated in sun products (such as Benzotriazine and Benzotriazole) and the presence of copper in the swimming pool water.

This coloring is limited to the water line (emerged part of the liner) because it is on the surface of the pool that the sun creams and oils, which are insoluble in water, float.

Products That Will Clean The Yellow Stains

  • Regular maintenance of the liner water line

The coloring of the water line is easily removed by a weekly maintenance , using a liquid, non-abrasive cleaning product (varnished membranes), provided for this purpose.

You can also use a magic eraser to scrub your water line.

  • Beware of limestone on the walls of your pool

The lime deposits on the water line of your swimming pool facilitate the adhesion of fatty substances and complicates its cleaning.

Lime is easily removed by using a suitable acidic cleaning product 

It is also possible to use a mixture of isopropyl alcohol and water (1/1). Very stubborn pollution is generally removed with ethyl acetate or THF, but these modify the appearance of the surface (shine) and also remove the varnish and the pattern, in the case of a coating printed or varnished. The use of ethyl acetate, THF or, more generally, PVC solvent, is therefore strictly prohibited with varnished and / or printed membranes.

  • Watch out for copper and sunscreen in your pool

Avoid an excess of sunscreen and especially sun oil (the worst!) And take a shower before swimming.

Avoid adding copper to your pool (copper sulfate).

How To Eliminate The Yellow Stained Water Line For Good

In order to remove the yellow stains on the liner or the PVC membrane, the following curative treatment must be carried out:

1st week:

1- Increase the water level of the pool to cover the stained area

Day 1 :

2- Perform shock chlorination at 10 ppm of free chlorine

3- Adjust the pH of your water to 7

4- Pour into a skimmer 1 cap (40 ml) of metal inhibitor (FERAFLOC) for every 50 m³ of water

Day 4:

5- Pour a new dose of 40 ml of FERAFLOC for every 50 m³ of water

Day 7:

6- Backwash the filter

NB : Let the filtration run continuously, throughout the treatment and repeat the above operations for 5 weeks.

How To Remove Stains From a Pool

It is the dread of any pool owner: seeing spots appear on the coating of a pool. Often difficult to remove they quickly become a nightmare. All stains are not cleaned in the same way, for the simple reason that they do not all have the same origin. The treatment will also depend on the coating of your pool: liner, coating, or fiberglass. Here is our guide for how to remove stains from a pool.

How To Remove Stains From a Pool Liner

Brown spots. Removing brown spots on the liner of your pool can be a relatively easy operation if they result from the presence of organic waste or are a sign of deposits of dead algae. On the other hand, it promises to be more delicate if it is a question of micro-mushrooms which, in reality, have developed behind the liner, on the concrete part of your swimming pool, and appeared by the effect of porosity. It is generally the consequence of humidity that settled between the coating and the concrete.

How do you know if it’s algae or fungi?

If the spots reappear quickly after rubbing them, it is fungi. In this case, do the following:
Lower the pH to 6.8 and stop the filtration. Thus, the pores of the liner will dilate and the treatment will be more effective. Then, if you have only a few isolated sections, bring gloves, a chlorine tablet, and diving goggles and then rub in small circular movements, without pressing too hard, on the stain.

On the other hand, if the spots are almost everywhere in the pool, pour with a watering can sodium hypochlorite or, failing this, bleach as close as possible to the spots.
Finally, raise the pH to 7 or 7.2 and then filter the pool water continuously for 72 h before washing the filter.

If the waterline has turned yellow. This is due to the presence of floating fatty substances on the surface of the water. Even with regular maintenance of your pool, sunscreens, are formidable. To prevent the appearance of this famous yellow line, think of rubbing the edge with a suitable product, once a week.

To prevent the appearance of limescale, which promotes the adhesion of fatty substances, by also using an acid cleaning product. If, on the other hand, the water line is crusted, do as follows:
Fill the pool so that the water largely covers the yellow line.

Do shock chlorination. Set the pH to 7. Pour a metal inhibitor into the skimmer at the doses indicated (generally 40 ml for 50 m3 of water). On the 4th day, pour a new dose of product. On the 7th day, backwash the filter. Leave the filtration continuously on for the duration of the treatment.

Rust stains. They reflect the presence of metals in water (iron, copper, manganese). To remedy this, apply the specific products using a sponge after putting on gloves. You can also try white vinegar. To do this, attach a sponge to the end of a hollow tube and pour the liquid into it. Then rub on the stains.

Pink or Red spots. Viscous in appearance, they first appear on plastic surfaces (water toys, ladders, etc.). To make them disappear, lower the pH to 7 and scrub the stains with a sponge. Then do a shock treatment or use an algaecide.

For optimal efficiency, also leave contaminated objects in the water during the operation. The filtration system must also work continuously. Then 24 hours later, raise the pH to 7.2 and 7.6 and leave the filtration system on for another 72 hours. Wash the filter every day before the treatment. You can remove stains on a liner by using a specific cleaner sold in specialized stores.

You will apply it using a sponge or a glove, and scrub in circular movements. You can also use silver stone, which is a natural clay-based solution, or white vinegar.

How To Remove Stains From A Fiberglass Pool

Red, Black, Brown, Blue/Green spots. This may be due to the decomposition of organic matter (leaves, insects, etc.) or an excessive supply of metal ions.

What to do? The treatment of these stains on your fiberglass pool will take place over a week. On the first day, Acidify the pool by reducing the pH to 6, then carry out shock chlorination. Then add a ferrous ion product using the correct dosage. On the 4th day, add another dose of the same product. On the 7th day, backwash the filter. In the end, check that the pH has risen between 7.2 and 7.6 and then stabilize it. For prevention, be sure to keep the pH between 7.2 and 7.6.

Brown or Green spots. Have algae formed on the bottom and walls of your pool? To be sure, just see if they disappear on contact with a chlorine tablet. If this is the case, treatment is necessary. Practice shock chlorination then adjust the pH of the water to between 7.2 and 7.6 as well as the hardness. Run the filtration system all the time.

Then, do a flocculation treatment to increase the fineness of filtration and eliminate the algae in suspension. Allow a day to pass then brush the walls, wait for the residue to form at the bottom of the pool, and vacuum them directly to waste. Return the filtration system to normal operation.
To prevent algae from returning, it is advisable to use a pool cover which will thus block the photosynthesis process.

Brown or Black spots. They are undoubtedly fungi, which have formed due to insufficient filtration, or random cleaning of the pool. To remedy this, you will need to lower the pH to 6 in order to acidify the water, before initiating shock chlorination.
Note that to avoid the appearance of fungi, the pH should be kept around 6.8 and the chlorine level should be at least 1.5 mg / l.

White or Grayish spots. If they are rougher to the touch, it is tartar. Here is the solution. Acidify the pool water by reducing the pH to 6 and then, allow the pH to rise alone between 7.2 and 7.6. If it has not gone back far enough beyond the 7th day, use a product. If this was not enough to remove the stains, you will have no choice but to empty the pool to descale it.

Warning! Before emptying the pool, it is imperative to check that there is no water under the bottom, otherwise, it could rise and irreversibly damage your installation.


If you do not want limestone to return to the walls and bottom of your pool, you must regularly analyze the pH of the water and adjust it if necessary, between 7.2 and 7.6. In addition, it is essential to treat the water regularly (at least 3 times a year) with a suitable anti-lime.

Discoloration spots. This is no doubt due to repetitive shock treatment. The chlorine damages the Gelcoat coating of your fiberglass pool. Unfortunately there is nothing to do, except to empty the pool and redo the coating.


The water line turns fluorescent yellow. It is the sign of the presence of benzotriazoles or debenzotriazines present in sunscreens. Here are the steps to follow. Raise the water level to above the yellow line then adjust the pH between 7.2 and 7.6. Once it is done, carry out shock chlorination and add a metal-capturing product in the correct dosage.

In addition, if you do not clean the water line quickly after the first signs appear, then the coloring could become permanent.

Brown marks at the waterline. Fats, in addition to remaining on the surface, trap dirt. To overcome it, the water line must be cleaned regularly with a suitable product whose role is to prevent stains from becoming permanent. If the waterline resists this cleaning, lower the water level below the coloring and clean with a descaler.

How To Remove Stains From A Concrete Or Plaster Pool

Heavy metal is a pool’s enemy. I’m talking about the invisible metals dissolved in your pool water from sources like rain run-off, pool equipment, saltwater pool systems, or even your concrete pool deck surface. Bits of metal like screws or hairpins can make a nasty rust stain.

It’s important to know what kinds of metals are creating the stains in your pool. Here’s a pool stain chart as a guide for metal stain identification in pools.

Metals are certainly not the only cause of stains in a plaster-surfaced swimming pool. Leaves, berries, bugs, suntan oil, or even your water-loving dog can all contribute to staining. For plaster pool stains is to always start with the brushing and shock before going in with a bunch of trial and error stain removers.

These types of stains can be cleaned with good old fashion elbow grease using a combination of a PoolStone and pool shock. Pouring a bit of pool shock directly onto a stain works similar to bleach and is ideal for plaster surfaces.

Sequestering agents, commonly called Stain & Scale chemicals, can help keep minerals and metals in solution, locked up tightly at the molecular level, so they won’t precipitate, mix with other particles, and then attach to your pool surfaces.

Other Types Of Stains: These can include pool stains from mineral scale-like calcium and metals like copper, iron, or manganese. Minerals can come out of solution in hard water, and metals can enter from fill water that is high in metals, or from copper pipes or a pool heater exchanger – when water balance is not correct.

Removing Stains from a Plaster Pool

Granular pool shock or EZ Stain Remover for organic stains
Sequestering agents or A+ Stain Remover for metal stains
Stain Eraser or PoolStone for mineral stains
Enzymes for oily, dirty stains
Acid Washing for all plaster, tile and coping stains
Keep pool water balanced and brush often

Once again, having the correct water balance is important. Poor water balance can become corrosive or scaling, and both conditions can cause plaster pool stains by making it easy for minerals and metals to come out of solution.