Published – August 2026
Is your pool surface fading? Let's find out
If your swimming pool is starting to look lighter, patchy, or completely different from when it was first installed, you may be wondering what has gone wrong. Don’t worry it is something we hear a lot from our clients every day.
The good news is that color loss does not always mean your pool surface is fading or failing. There are several different reasons why a pool can lose its original color, and some are much easier to fix than others. Most pool surface manufacturers in the USA use pigment (color) that is very resistant to chlorine, bleaching and UV light.
Here are three of the most common causes of color change in swimming pools.
1. Calcium is covering the pool surface
New plaster and other cement-based pool surfaces continue to react with water after installation. This process is called cement hydration, and it continues for some time after the pool has been finished.
One of the by-products of this process is calcium hydroxide. It can move through the pool surface and eventually form a white crystalline calcium deposit on the surface. This deposit can cover the pigment in the pool finish, making the surface appear lighter, duller, or faded even though the original color is still underneath.
This is particularly important during the first few days after a new pool is filled. The National Plaster Council (NPC) recommends removing plaster dust (calcium residue) and filtering it from the water during the first 3–5 days. If it is left on the surface, it can carbonate and form calcium carbonate, which can be much more difficult and expensive to remove.
2. Minerals and metal have bonded to the surface
Minerals and metals in your pool water can also settle onto the surface and cause the color to change..
Calcium may create a white or dull film, while metals such as copper, manganese and iron can actually change the color of the pool surface. Copper and manganese can produce blue, green or black colors, while iron can produce red, orange or black staining.
This is why regularly testing your pool water for hardness and metals is important, particularly if you notice a change in the appearance of the surface.
Once metals or minerals begin accumulating, they can continue to affect the appearance of the pool. In some situations, sequestering or chelating chemicals such as Scale & Stain Eliminator can help keep metals and minerals suspended in the water rather than allowing them to precipitate onto the surface.
3. Bad water chemistry may have damaged the surface
This is the one pool owners really need to understand.
If pool water becomes too aggressive because the pH, alkalinity or calcium hardness is too low, it can begin to attack a cement-based pool surface.
Over time, the water can dissolve components of the cement matrix that holds the pigment in place. As the cement compounds are lost, the pigment can also be released.
This type of color loss can appear as faded, lighter-colored, or white areas across the pool surface. If aggressive water conditions continue for long enough, pigment can be lost deeper into the surface. Once the pigment has actually been removed, the resulting color loss is irreversible.
A simple rule for pool owners
Don’t assume that a faded-looking pool surface means the color has disappeared.
Sometimes the original color is still there but is being hidden by calcium or mineral deposits. Other times, metals in the water may have stained the surface. In more serious cases, poor water chemistry may have actually damaged the surface and removed some of the pigment.
The important thing is to identify the cause before trying to fix the appearance.
For a new pool, following the correct startup procedure is particularly important. After that, regular testing and good water chemistry can help protect the surface from mineral buildup and deterioration.
Your pool surface is a significant investment. Keeping the water properly balanced is one of the simplest things you can do to protect its color and appearance for years to come.
If you have any kind of discoloration in your pool and would like some help, please feel fee to reach out to us.
References
NPC Technical Bulletin #3 – “Swimming Pool Interior Finishes & Chemical Etching Deterioration” (ref #15, also underlies #5, #6, #9): Full PDF is live at npconline.org’s CDN — https://cdn.ymaws.com/www.npconline.org/resource/resmgr/technical_library/Technical_Bulletin_3_-_Swimm.pdf. This is the actual bulletin, not a summary.
NPC “Swimming Pool Start-up Procedures” (ref #14): Live PDF hosted by an industry partner — https://universalcement.com/wp-content/uploads/2017/03/NPC-Pool-Start-Up-Instructions.pdf
J. Thomas & H. Jennings, “The Science of Concrete,” Section 5.1 (ref #16): This is the exact section and even the exact figure (5-3) your blog cites — hosted directly by Northwestern’s Infrastructure Technology Institute: http://iti.northwestern.edu/cement/monograph/Monograph5_1.html
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