How to Remove Gray Stains on Fiberglass Pool Steps

How to Remove Gray Stains on Fiberglass Pool Steps

As a pool owner, I’m hyper-sensitive to any little thing that seems off with my pool.

The tiniest little piece of dirt won’t make it past my watch. I’m like a hawk when it comes to pool grime. So, when I noticed an unsightly gray waterline stain starting to form around the wedding cake pool steps, my OCD went into overdrive.

I immediately started researching why stains occur and the best way to clean fiberglass pool steps. This led me down a rabbit hole and me trying a bunch of different methods. Some work great. Others so-so.

So, to save you time, I’ll reveal my favorite way to clean fiberglass pool steps.

First, why do fiberglass pool steps get dirty?

Fiberglass pool steps can get dirty for a variety of different reasons.

The most common reason is people tracking in dirt and debris from the yard. This happens when you have kids or pets running around the pool area.

Another common reason is because of a chemical imbalance in the pool water. If your pH levels are off, it can cause staining on fiberglass surfaces.

Lastly, hard water can also lead to staining on fiberglass pool steps. Hard water is water that has a high mineral content (like calcium and magnesium). When the water evaporates, it leaves behind these minerals, which can then lead to staining.

How to Clean Fiberglass Pool Steps (Gray Stain Removal)

Different color pool stains can form on fiberglass steps due to variety of reasons. In this article, I discuss how to clean gray stains. If you have yellow or brown stains on your steps, I’d recommend checking out Jack’s Magic Step Stuff, a commercial cleaning product that targets those tougher metal stains.

I have pretty hard water at my home. A week or so after I add water to my pool from the garden hose, it might start to recede a little. This is normal as I use the pool a lot and it gets a lot of direct sunlight. So, there is some normal water loss.

When the water starts to drop below the first step is when I can start to notice the remnants of the hard water. An unsightly gray stain from the calcium build up will start to appear.

To be honest, when I first noticed this, I thought it was just dirt. I actually just tried taking a scrub brush, wetting it, and putting in some old-fashioned elbow grease. But the stains just wouldn’t budge.

Use Magic Eraser

After my futile efforts of using a scrub brush, I turned my attention to other household cleaning products. The first one I tried was a Mr. Clean Magic Eraser.

I had read online that people had used these to clean their boat hulls and other fiberglass surfaces, so I thought it was worth a shot.

I went ahead and wet the eraser and started scrubbing the waterline on my pool steps. It took a little bit of effort, but the stains started to come up immediately. I was amazed at how well it worked.

After I was done scrubbing, I rinsed the steps off with some clean water from the hose. And voila! The steps looked brand new again.

The Mr. Clean Magic Eraser is definitely my new go-to method for cleaning fiberglass pool steps. Not only is it effective, but it’s also super easy to use.

If you have hard water stains on your fiberglass pool steps, I highly recommend giving this method a try. You won’t be disappointed.


In this article, we discussed the reasons why fiberglass pool steps get dirty. We also talked about my favorite way to remove gray stains due to calcium buildup.

If you have hard water stains on your fiberglass pool steps like me, I highly recommend using a Mr. Clean Magic Eraser. It’s super easy to use and it does an amazing job of removing stains.

I’d also recommend testing your pool water frequently. There are specialty Pool Water Hardness Strips that you can use to test the hardness of your pool water. If the levels are too high, it can cause staining on fiberglass surfaces. You can get ahead of this by adding fresh water or using chemical water softener.

About the Author

stefan schulzStefan Schulz is the founder and owner of PV Pool Cleaner. He spent his college years working at Niagara Pools and Spas, one of the largest Swimming Pool and Hot Tub Dealers in the Eastern United States.

Today, he utilizes his background, experience as a pool owner, and the resources of his digital marketing agency, Orpical Group, to generate informative and engaging content for pool owners everywhere.