Do the walls of your pool appear to be filthy all the time? Not a huge fan of swimming because they look so dirty and gross? We don’t blame you. Stained pool walls are ugly, and they can definitely put you off from enjoying your swimming pool. But here’s the good news: stains aren’t forever. With just a little bit of basic swimming pool maintenance knowledge, you can easily identify and remove those nasty-looking stains and even prevent them from returning.


Take a look below for what you need to know.


How to Identify What Stained Your Pool

Most pool stains are caused by some type of organic matter or metal, which is important because the source of the stain determines the best way to remove it. If you don’t use a pool cover, there’s a good chance your stains are from leaves or other yard debris. If your pool is full of well water or it has copper plumbing or corroded metal equipment, metal is a likely culprit.


If you’re unsure what might have caused the stains in your pool, here’s how to identify the most likely culprit by stain color:


●        Green/brown/red stain. This color combo indicates the presence of iron in your pool water. These stains are common in pools filled will well water and those that have iron sources (such as a metal fence) near the pool.


●        Red/blue stain. Bright stains are most commonly caused by berries. If you have berry-bearing shrubs or trees near your pool, those are probably the culprit.


●        Brown/black stain. Stains that look brown, black, and purplish are usually caused by high levels of manganese in the water, which is fairly common in municipal water supplies.


●        Green/brown stain. Green and brown stains are almost always caused by plant matter that has made contact with the walls of the pool for extended periods.


●        Green/black/blue stain. Stains of this color are commonly caused by organic matter like sticks, leaves, and other yard debris. However, they can also be caused by copper, so if you don’t have a lot of organic matter near your pool, corroded copper plumbing may have caused the stains.


Perform a Stain Test

Once you’ve got a solid idea of the culprit behind your pool stains, you’ll need to test your theory by performing a stain test. Here’s how to do that:


●        Test for metal stains. Try applying a small amount of chlorine directly to the stain. If it was caused by metal, the chlorine will have no effect on it. Next, try applying a small amount of ascorbic acid powder (vitamin C) to the stain. If the powder lightens or fully removes the stain, metal was the culprit.


●        Test for organic stains. Apply a small amount of chlorine directly to the stain. If it was caused by organic matter, the bleach should lift it easily.


How to Eliminate Pool Stains

Once you’ve confirmed the culprit behind the stain, it’s time to start scrubbing. As mentioned, chlorine is highly effective at getting rid of color left behind by organic matter, so that’s what you’ll use for those types of stains. But since there’s likely already chlorine in your pool water, you’ll need to hyper-chlorination route using a calcium hypochlorite shock treatment. Make sure you do this at dusk to allow the chlorine adequate time to work.


To remove stains caused by metal, you’ll need to use specialty stain remover formulated for the type of metal that caused the stains in your pool. If you’re unsure what type of metal is the culprit, consult a swimming pool maintenance specialist to ensure you get the right type of stain treatment for your needs. 


If the staining in your pool is really bad, it may be time to consider resurfacing your pool by getting it acid washed.


Best Ways to Prevent Pool Stains

Once you’ve tackled all your pool stains, preventing them from returning is simple, but it will take some diligence. Here’s what you need to do:


●        Keep your pool water at the proper pH at all times and make sure there’s adequate sanitizer, too.

●        Vacuum your pool weekly or use a robotic pool cleaner to keep leaves and other debris from sitting on the surfaces of your pool.

●        Skim organic matter from the surface of your pool whenever you notice it.

●        If you have fruit-bearing trees or bushes near your pool, consider moving them far enough away to prevent organic matter from blowing into the water.

●        Examine your pool for stains weekly. If you notice the beginnings of a stain, prompt removal is the best way to prevent it from growing severe.


If you’re not a fan of DIY pool maintenance or don’t have the time, it’s in your best interest to set up a weekly or bi-weekly swimming pool maintenance schedule with a pool care company. If your pool is prone to staining and you don’t stay on top of it, you’ll end up having to resurface your pool more frequently than is really necessary.


Royal Pool & Spa: Your Twin Cities Source for All Things Swimming Pool Maintenance

Tired of dealing with pool stains? Want your swimming pool to look crystal clear all the time? Then get in touch with our team at Royal Pool & Spa to set up a weekly or bi-weekly swimming pool maintenance schedule! All of our pool techs have a minimum of 10 years of experience in the industry, and we’ve proudly served White Bear Lake, MN and the surrounding areas since 1988. To get started, give us a call today at 651-779-7606 or request a quote and we’ll be in touch!