Why Do Swimming Pool Stairs Turn Yellow?

Stair around outdoor swimming pool

For most pool owners, having a swimming pool is a source of relaxation and enjoyment. Because you want your pool to be in tip-top shape at all times, it can be stressful when you start to notice discoloration or a yellow tint on your pool stairs. 

Not to worry! We will walk you through possible causes of your pool stairs turning yellow and how to fix them. Your swimming pool will be in perfect condition soon enough!  

Mustard Algae 

Mustard algae is a type of green algae found in many swimming pools because it is chlorine-resistant. But don’t let this scare you–with the right amount of chemicals and cleaning, you can conquer mustard algae and preserve your pool. True to its name, you’ll recognize it as the yellow-colored stain or tint spreading across your swimming pool steps.

While this type of algae is not initially harmful to humans, it can attract more aggressive, harmful bacterias. If left untreated, mustard algae can create a slippery film on your steps and cloud the water, decreasing visibility.

Organic Stains 

Organic stains refer to discoloration caused by leaves, branches, mulch, or algae blooms. Also referred to as vegetable stains, organic stains may be particularly noticeable after a storm or hard rain. If you allow clumps of leaves to sit in the pool, the organic material can stain the pool’s floor, walls, and steps.

Over time, this accumulation of organic materials and minerals can result in a yellow-tinted film covering your swimming pool stairs. It’s best to attack these stains early on rather than let them sit for an extended period.

Mineral Stains 

Another possible cause of a yellow tint on your pool stairs is iron in your water supply. High iron levels can stain various items around your pool, including concrete and vinyl-lined surfaces, ladders, and your pool stairs.

Iron tends to oxidize as it enters the water supply, causing orange or rust-colored stains, which really stand out against the blue hues of a swimming pool.

Calcium buildups can also occur if your pool’s pH levels are unbalanced. A high amount of calcium in the water will cause deposits to form on your pool’s steps, making them appear white or yellowish. A calcium buildup is most common when you have hard water and if your maintenance is not thorough enough. With time, this deposit will spread outwards, covering more and more of the surface area of your pool stairs until it becomes too difficult to clean off. 

What Can You Do?

The moment you notice discoloration on your pool steps, treat your pool right away. Act quickly to save time and money and get your pool back in working condition.


Decontamination is crucial for mustard algae removal. Because the microscopic algae spores can cling to other materials, make sure to bleach and deep clean all swimming suits, pool toys, and pool cleaning supplies and brushes.

Professional Treatment

If you have particularly stubborn pool blemishes, professional pool cleaners can help remove tough stains and discoloration from a swimming pool. They have the experience and expertise to use the right chemicals and treatments to get the job done.

Shock Treat Your Pool

Shock treatment is a process in which 1 pound of chemicals is added to the pool for every 10,000 gallons of water. Pour the shock solution around the pool and leave it overnight to filter. 

The intense chemical treatments can be very helpful when removing tough stains like mustard algae or mineral deposits that don’t come off easily on their own. Make sure to vacuum your pool afterward to clean up debris.

Regular Care

And, of course, make sure to care for your pool daily. Daily care makes all the difference in preventing algae growth and stains.

  • Test your water every two weeks to ensure chemical levels are optimal.
  • Brush down pool walls and steps once a week. Make sure not to ignore corners or hard-to-reach areas near the steps.
  • Sweep up any leaves or other debris that always seem to end up in your pool.
  • Clean out the skimmer basket every few days to prevent debris from being pulled back into your filtration system.
  • Run the vacuum frequently.

Give Your Pool the Love it Deserves

Now that your pool is in perfect condition, give it the extra attention and care it deserves with Pool Icons’ luxury features

Sprucing up your swimming pool with an elegant fountain or water feature will help your pool circulate chemicals and stay clean while also providing a serene environment. Adding personal touches like a fire element or custom pool lights puts the cherry on top of your newly restored swimming paradise.