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? 

The waterline of a swimming pool is a very sensitive area (especially when it is equipped with a liner). This is where most of the dirt collects, resulting in a brown or yellow stain on the water line.

The staining of the waterline is caused by fatty substances and debris floating on the surface of the pool water, which includes, body oils and fats and pollution from the environment.

Unfortunately, the water line is more easily stained because it is more exposed to the sun. In fact, the discoloration of the liner is caused by the sun’s radiation.

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

This yellowish color is a result of a chemical reaction between certain anti-UV agents incorporated in sun skin products (such as Benzotriazine and Benzotriazole) and the presence of copper in the pool water.

This yellowish color shows on the water line because sun creams and oils are not soluble in water but float on the surface of the water.

How To Prevent Yellow Pool Liner Stains

  • Regular pool water maintenance

The coloring of the water line is easily avoided by weekly pool maintenance.

  • Keep your pool water chemistry balanced.
  • Keep debris/dirt out of the pool, and don’t let leaves or dirt sit on steps or on the pool floor. 
  • Use metal sequesters to keep metals from building up.
  • Use a pool cover to keep dirt and debris out.
  • Brush and vacuum your pool at least once a week.
  • Shock your pool regularly (about once a week).
  • Beware of limestone on the walls of your pool

The lime deposits on the waterline of your swimming pool facilitate the adhesion of fatty substances and complicate’s 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 stains are generally removed with ethyl acetate or THF, but these change the appearance of the surface (shine) and also can remove the varnish and pattern of a liner. The use of ethyl acetate, THF, or, more generally, PVC solvent, is therefore strictly prohibited with varnished and/or printed liners.

  • Watch out for copper and sunscreen in your pool

Avoid excess sunscreen and especially sun oil (the worst!) Take a shower before swimming.

Avoid adding copper to your pool (copper sulfate).

How To Remove Yellow Stains From A Pool Liner

In order to remove the yellow stains from the liner/PVC membrane, the following treatment must be done:

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 pump run continuously during the treatment period.