Stains on vinyl pool liners

Vinyl-lined pools are usually quite stain-resistant.  This is because they are smooth, have fancy protective coatings, are smooth to the touch, and are almost completely nonporous. This is the perfect combination for keeping stains and algae away. However, there are times when minerals, manganese, copper, or even organic stains can appear as stains on vinyl pool liners.  Don’t worry we have a treatment that can resolve these issues for you.

Most of the time our stain treatment kit will work wonders on vinyl pools.  Our stain Treatment Kit restores the colour and smooth finish within a few days.  You will not have to drain the pool water to remove the stains.  Our treatment works with the water still in the pool.

vinyl liner pool stain
This vinyl lined pool had very severe and widespread copper staining throughout the pool.
vinyl liner pool stain
The copper staining over the vinyl has been completely removed. The client did not have to drain the pool to remove the stains.

Causes of Stains on vinyl pool liners

Organic Stains

These are usually from dirt and algae that have since been killed off but the stains still remain.  This is often known as non-living organic material.  This will usually happen in corners and areas of reduced water flow. Also, tannins from leaves and vegetation cal often leave a brown tint covering the entire pool surface.   This type of staining usually takes a while to form and can be very difficult to remove with brushing or chlorine.

Iron or copper stains

Copper stains are often a teal or blue colour and will often get darker or look worse after shock chlorination.   The picture at the top of the page is a severe case of copper staining that we have removed.  Iron stains can be more of a brown colour and sometimes will partially wipe away with a brush but will soon resettle again and stain the pool.

Chemical Damage

Severely low alkalinity for even calcium hardness can cause damage to the pool vinyl surface.  This is because the water is unbalanced and is seeking to rebalance itself.  To do this the water destroys the vinyl slowly over time.  This type of staining can be very difficult to repair.  Elevated chlorine levels for an extended period can also cause permanent damage to the liner.  As strong as they are, liners are not designed to withstand high chlorine levels for a long time.

Microbial Organism Staining

Stains on vinyl pool liners are usually copper or mineral-based.  While calcium and algae can stain vinyl, these types of stains are less common and usually easily removed. Likewise, fungus and bacteria stains are also uncommon but we do see them from time to time. Stains like this appear because dye-producing microorganisms gather on the underside of the vinyl and cause discoloration.   After a while, this staining will start to appear on the top of the vinyl and thus become visible to the pool owner.  These will appear like gray stains on the sides or bottom of the pool.

Some publishers argue that this type of staining can be removed with shock chlorination and a quality copper-based algaecide.  Our experience with clients who have this issue is that this process does not work, or only works for a short time.  This is because the stains are coming from under the liner not on the top surface of the liner.  We are currently investing in further research on this issue.

If you have this issue and you are considering replacing the liner then it would be a great idea to have the sand base of the pool pretreated before you install a new liner.  There are several options available for pool owners.  It is a good idea to talk to your vinyl supplier about which one would be best suited to your situation.

Remember, mineral and copper stains are very stubborn and won’t brush away.  To remove these types of stains our treatment process is your best option.

Vinyl liner with organic stains
This vinyl liner had organic staining on the surface that would not react with shock chlorination or scrubbing.
organic staining on vinyl pool
The stain treatment kit we supplied remove these stains without draining the water. The kit had no chlorine and no algaecides.


My pool liner is fading

Usually vinyl lined pools will fade very slowly over a long period of time.  It is not uncommon to see 15-year-old vinyl pools that look close to the original colour.  Modern vinyl has great UV resistance and is usually a lot stronger than some products used in the past. So, chances are, you may have a mild calcium formation or mineral contamination on the surface rather than a faded vinyl pool liner.

How can I stop my pool liner from fading?

To extend the life of a vinyl pool liner it is best to keep the water chemistry in balance.  This can be done by regularly testing and balancing the pool water.  As a rule, vinyl does not like aggressive water that is very high or very low in pH.  It is also not very resistant to high chlorine levels.  Often we find that high chlorine levels lead to premature fading and breaking down of the vinyl surface.  In short, keep your water balanced and you will save a lot of money by not replacing your pool liner sooner than required.