That’s puzzling. What’s that stain in our swimming pool or on our pool deck? Just as the shower or bathtub in the house may seem to “all of a sudden” have a stain or a ring around it, chances are, it didn’t happen overnight.

Stains and build up occur over time, but unless you’re paying careful and close attention to your swimming pool, a potential staining hazard may go unnoticed until it’s become a problem that can no longer be ignored — like ring around the bathtub!

How To Identify And Remove Swimming Pool Stains

Getting to the bottom of stains

IF your swimming pool is staining, you can call a pool contractor to come and diagnose the issue or you can bring in a sample of your pool water for testing to a pool service contractor. There are also “stain identification” kits on the market that allow you to self-diagnose and pinpoint the problem and then you can choose the right treatment for the staining.

There are myriad types of stains that can plague your swimming pool with decaying organic debris being the biggest factor. This debris includes leaves, twigs, berries and other items that fall to to the bottom of the pool and decay. Organic stains typically leave brown stain marks.

Swimming pool staining typically occurs when excess organic or metal compounds meet pool water that is improperly balanced. When you have incorrectly balanced pH, alkalinity and sanitizers you are setting the stage for a perfect storm of stain-causing elements.

Organic staining

With this type of stain you will see a noticeable mark or outline. Organic staining can be caused by leaves and/or dirt. Organic staining can be addressed by raising the chlorine level in the water or by rubbing a chlorine tablet right over the stained area and it should come right off. Organics will usually leave a stain in the shape of the item — ie a leaf or berry.

Metal staining (Copper)

A metal stain in your swimming pool can be cleared up with Vitamin C tablet or with a commercial pool cleaning agent — ask your pool contractor for advice. If you have a white pool that is suffering from multiple metal stained areas you may want to consider an acid wash for the pool as this will clear away the staining and make the area bright and white again.

Metal or copper staining will give your pool a dull, brown stained area that can dull the entire look of your swimming pool. Metals are naturally occuring in water but their presence becomes problematic in the pool when they leach and react to other metals in the pool such as plumbing or pool heater fixtures.

Calcium staining 

These stains look like little brown spots in the pool. Calcium staining occurs when calcium levels get too high and causes the calcium to leach from the swimming pool and stain the pool itself. Calcium stains can be removed by sanding them down (a task probably better left for a pool contractor) or by acid washing the swimming pool.

cleaning dry pool

Mottling of the pool plaster

This occurs during the mixing of the concrete or plaster for the pool and appears as dark, mottled stain patterns on the pool walls and floors. If the pool is new the pool contractor can do a “zero alkalinity” treatment to address the mottling and make the pool look beautiful again.

Stain testing 

In most cases, the best way to correctly identify a pool stain is to use a stain id kit.  For iron, try a simple test first with vitamin C tablet; hold the tablet against the stain and if it gets lighter or disappears altogether, the stain you’re looking at is metallic. If you suspect the stain is caused by decomposed oirganic debris, hold a trichlor tablet against the stain; if it lightens, it is organic staining.

Treating stained areas in your swimming pool may not be a “one and done” event. You may need to not only be diligent in cleaning the stains, but for the health and longevity of your swimming pool, you need to get to the root cause of the staining and address it. Merely clearing away stains is only a short term fix. If you can’t get to the bottom of the staining on your own, we urge you to call on the services of an experienced swimming pool contractor who can help.

A swimming pool is a major investment and one you want to keep viable and operational and beautiful for decades!