When you spot a stubborn stain on your fibreglass swimming pool, it can feel like it’s ruining the look of your entire backyard. Ottawa summers are short, and pool days should be stress-free. But stains can put a damper on that experience, especially if they don’t come off with a quick scrub. Whether it’s an ugly brown ring at the waterline or dark blotches on the pool floor, the problem tends to stick around longer than you’d like.
Fibreglass pools are popular for good reason. They offer a smooth finish, are easier to maintain than some other types, and look amazing when clean. Still, staining is a common issue if water balance or upkeep slips for even a little while. Staying on top of maintenance and knowing how to treat stains is key for keeping your pool clear, clean, and ready for use all summer long in Ottawa’s warm season.
Understanding Common Stains
Not all pool stains are the same, and in fibreglass swimming pools, treating each one properly matters. The smooth surface of fibreglass can make stains a little easier to prevent, but once they show up, they often stick firmly. Knowing what you’re dealing with is the first step to cleaning it.
Here are some of the most common stains you’ll come across in a fibreglass pool:
1. Organic stains
These come from leaves, twigs, berries, insects, or algae. If debris isn’t removed quickly, it can leave behind brown, green, or even purple marks.
2. Metal stains
These are usually caused by metals like iron or copper in the water. You might notice reddish-brown or blue-green spots, depending on the type of metal.
3. Algae stains
Especially after heavy rainfall or inconsistent chlorine levels, algae can cling to the pool’s surface and cause large dark patches. These are often slimy when touched and may keep returning without proper treatment.
4. Waterline stains
A dirty ring around the pool near the tile line is often caused by oils, sunscreen, and dirt gathering where the water meets the edge. It’s more of a cosmetic issue but can still be tough to remove.
Some stains get worse because of poor water chemistry or because they’re ignored for too long. For example, if your pool water is high in iron and you shock it suddenly, iron particles can oxidise and stain the surface. Or if you let leaves sit at the bottom for a few days, tannins can soak in and leave an imprint.
A good example is a customer who once noticed blue streaks running down their pool stairs. It turned out to be copper build-up from untreated source water. Stains like that don’t wipe off with elbow grease alone. They need a more specific approach, matched to the stain you’re dealing with.
Understanding what has caused the discolouration will help shape the next step—choosing the right cleaning method and avoiding damage to your fibreglass surface.
Effective Cleaning Techniques
Once you’ve figured out what type of stain you’re dealing with, you can be more strategic about how to clean it. Fibreglass pools need a gentler touch than concrete or vinyl ones. Scrubbing too hard or using the wrong product can actually scratch the surface or make the stain worse.
Here’s how to deal with the most common stain types safely and effectively:
– Organic stains: These are usually the easiest to remove. Often, a non-abrasive brush along with a pool-safe oxidiser like chlorine can lift the stain. It helps to address these early before they set deep into the surface.
– Metal stains: These are trickier. They often require a stain remover made specifically for fibreglass pools. Many pool shops carry products that target iron or copper buildup without damaging the gel coat. You can also try a pH-lowering process to draw out the stain slowly, but that needs careful monitoring.
– Algae stains: Algae might seem purely like a sanitising issue, but the stains it leaves behind can be persistent. Using a pool algaecide in combination with brushing can help. In more stubborn cases, professional cleaning might be the safer route to avoid affecting the pool finish.
– Waterline stains: If you’re dealing with sunscreen residue or oils, specially formulated gel cleaners can stick to the vertical surfaces long enough to loosen the grime. Avoid regular household products since many aren’t safe for pool use.
One mistake pool owners often make is using abrasive tools like steel wool or rough brushes. These can seriously scratch fibreglass, creating spots where algae and dirt grab on more easily in the future. Stick to soft-bristled brushes and stain removers that state they’re safe for fibreglass. If you’re using any product for the first time, test a small area before doing the whole pool.
Preventative Measures That Actually Work
The best way to make stain removal easier is to stop stains from forming in the first place. A bit of routine effort pays off big time, especially in places like Ottawa where pool season is packed into a few key months of the year.
Here are a few reliable ways to protect your fibreglass pool from stubborn stains:
– Test and balance water weekly
Keeping pH, alkalinity, and sanitiser levels within the right range can prevent metal and algae issues. If you’re unsure what ideal levels look like for a fibreglass pool, consult a professional instead of guessing.
– Keep organic debris out
Skim leaves, bugs, and everything else out of the pool as soon as you see them. Use a pool cover during storms or when the pool’s not being used for long stretches.
– Regular brushing
A soft sweep once or twice a week helps keep tiny algae spores and dirt from sticking to the surface. Focus on corners and steps where particles tend to settle.
– Use a quality pool cover
It keeps out falling leaves, dust, and sunlight, which all contribute to stain problems. Even short-term use, like overnight or on especially windy days, can make a difference.
– Watch for metal in your water source
If you’re filling your pool from a well or suspect that your tap water has iron or copper, use a metal sequestrant during fills to catch the particles before they land on your pool surface.
Keeping these habits going even after the start of summer is what keeps your fibreglass pool looking great from June through to September. The weather might be warm, but water chemistry can change quickly, especially with increased sun exposure and more use.
When It’s Time To Call In The Experts
If you’ve brushed, adjusted your chemical levels, and tried safe cleaners without seeing any results, it’s probably time to bring in a pro. Some stains have already seeped into the gel coat or have been building up for a while, making them tough to remove without professional tools and experience.
There are also situations where trying to scrub a stain away can backfire. For example, repeated attempts to treat a copper stain without knowing the metal levels in your water can spread the problem around the pool. A professional can test, identify the source, and treat the stain without harming the surface.
No one wants to schedule help mid-summer, but if you’re fighting the same spots over and over again, it’s usually worth letting someone come take a look. Stubborn stains often mean there’s a bigger issue at play, whether with your filtration, water supply, or pool materials. Catching it early can save you from shelling out for resurfacing later.
How To Keep Your Pool Looking Great This Summer
Stains happen, especially with trees, rain, or heavy use, but that doesn’t mean you’re stuck with them. Learning the source of the stain, choosing pool-safe products, and acting early go a long way when it comes to fibreglass pools. Add routine brushing, water checks, and a decent pool cover to the mix and you’ll already be ahead of the game.
Fibreglass pools need a little attention but give back a lot in ease and comfort. Once you know what signs to watch for and what methods to avoid, it’s way easier to keep your pool looking like new. Whether you’ve had your pool for years or it’s your first summer enjoying one, staying on top of these small tasks makes all the difference.
Ottawa summers should be spent enjoying your pool, not stressing over stains. Regular maintenance and early action can keep your pool looking stunning all season long. If you’re considering a refresh or dealing with persistent stains in your fibreglass swimming pool, take the next step with Impressions Group Ottawa Inc. Let us help you enjoy clear, inviting water all summer.