Stains and Discoloration in a Vinyl Liner Pool


When your pool and backyard is as post card pretty as this pool, the last thing you want are stains on your vinyl liner pool.

Aboveground or inground pools, both use vinyl liners, and are susceptible to staining from minerals, organic materials and chemical damage.

For all of you vinyl liner pool owners, here’s how to identify, treat and prevent staining of your vinyl liner pool.


One advantage of vinyl pool liners is that the slick surface often reduces mineral staining. It’s not uncommon to see the pool stains more pronounced on plastic and metal items in the pool, such as on your ladders, steps and pool lights.

Vinyl liners also can stain, in localized areas, or spread throughout the pool surfaces. It can be just one small spot, or only at the waterline, on on the pool steps. Size, color, location and any “behavior” of the pool stain can be helpful in identifying the source or cause of the stains.

copper-test-stripsTesting your pool water for mineral content can also be helpful to identify pool stains. Your local pool store may be able to test your water for iron, manganese or copper. We have copper test strips available in our pool test kit department.

Mineral Pool Stains

Mineral pool stains can be every color of the rainbow, but a few are more common. Blue/Green stains are usually from too much copper in the water. Iron pool staining can be brown, red or a yellow / orange color. Calcium or sodium salts can leave whitish deposits on your pool liner.

For stains on a horizontal surface, you can test the surface for mineral staining by using a small amount of acid on the stain. Place a vitamin C tablet, (ascorbic acid) on the stain for a short time period. You can also use pH decreaser (sodium bisulfate) placed into a sock. If the stain lightens considerably, you have a mineral stain on your hands.

Organic Pool Stains

Organic stains come from dead algae, or other small animals, or from the tannins contained in leaves and plant debris. Organic stains can stain a range of colors, from yellow to brown to black. These stains normally occur after a long winter, or after a big thunderstorm.

Organic chemicals respond to chlorine applied directly on the surface. Sometimes just shocking the pool will lighten or remove organic pool staining. Place a chlorine tablet on a stained area for just a few minutes. If the stain lightens, then you have an organic pool stain.

Chemical Damage

Fading can occur from the sun naturally over time, or vinyl liners can become “bleached” from high chlorine or low pH levels. Broadcasting granular chemicals into a vinyl liner pool is generally a no-no, instead pre-dissolve into a bucket of water first. Chemical or UV damage is not considered a stain on the pool surface, and is generally not treatable.

jacks magic stain-ID kit helps you determine which steps to take next to remove your pool stainsUnsure of which type of vinyl pool stain you have? The Jack’s Magic Stain ID kit helps you determine what the next best steps would be to remove your particular type of pool stain.


To begin treating a pool stain, the first step to take (after identification) is to balance your pool water chemistry. In some cases, merely adjusting the pH, Alkalinity and Calcium Hardness levels can lighten or remove some types of pool stains. Use a fresh pool test kit or test strips, and adjust your pH to 7.5 – Alkalinity to 100 – and Calcium Hardness to 200.

Mineral Pool Stainspool chemicals for stain removal and prevention

Generally speaking, mineral pool stains respond best to a treatment with acids. Plaster pools may be acid washed, or a stain-master used for localized rust stains – but you can’t acid wash a vinyl liner pool, can you?

Vinyl pool stains can be removed with acidic stain removal products like Stain Free, or A+ Stain Remover, or Jack’s Magic Blue Stuff for vinyl liners. If the stain is on your vinyl pool steps, try Jack’s Magic Step Stuff.

Organic Pool Stains

Generally speaking, organic pool stains respond best to a treatment with oxidizers. For plastered pools, you can just dump powdered shock right onto the bio-stain, and watch it instantly disappear, but you can’t do that with a vinyl liner pool, can you?

Organic pool stains can deposit themselves only around the main drain, or on the steps, or corners of the pool. Balance the chemistry, add super pool shock, according to directions. If that doesn’t remove the organic stains, try one of the products listed above. Safe for vinyl liners, and they work for both mineral and organic pool stains.


Keeping your pool water balanced and the pool clean, especially during the off-season, is important for keeping your pool stain free. If your pool water comes from a well, it may contain high metals and minerals. And of course, always use stainless steel screws on your ladders, lights, steps and faceplates – and ban the use of hair ‘bobby pins’ in the pool.vinyl-pool-stain-prevention-chemicals

To control pool stains from metals and minerals, use Jack’s Magic Purple Stuff or MetalFree. Our own Super Stain Away is very popular, and for severe mineral and metal issues, CuLator will reduce levels.

These stain prevention pool chemicals control pool staining by making it difficult for minerals in the water to precipitate out of solution, where it can stain your vinyl liner, steps or ladders.

No one likes stains in their vinyl pool! If you have been battling pool stains, and are finding it difficult to resolve, give our pool stain experts a call here at 800-288-7946!



Davy Merino
InTheSwim Blog Editor


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