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Why is Swimming Pool pH Level So Important?

Why is it important to maintain the right pH balance in your fiberglass swimming pool

The correct pH level not only keeps your pool water clean but also protects your pool equipment, like the heater and pump. 

Maintaining the correct pH also helps your pool finish to last longer and not discolour. While fiberglass pools are nonporous and naturally resistant to water issues like algae growth, pH still plays an important role in the proper maintenance of your pool.

What Does pH Mean?

The term pH is a way to measure how acidic or basic the water in your swimming pool is. It’s really important for keeping your pool water balanced.

The pH scale goes from 0 to 14, where 7 is right in the middle and considered neutral. Anything below 7 means the water is acidic. If it’s 8 or higher, it’s basic or alkaline. This is different from total alkalinity, although they can affect each other. The right pH level for your fiberglass pool should be between 7.2 and 7.8.

The water can be harmful if your pool’s pH goes below 7.2. It can damage the pool’s surface and metal parts, making it harder to keep the chlorine working. Chlorine is a sanitizer that works better at a lower pH, but the chlorine in low-pH water isn’t as stable, so you’ll end up using more of it.

On the other hand, if the pH goes above 7.8, you might see problems like cloudy water and scale buildup. Scale is mostly made of calcium, and calcium doesn’t dissolve well when the pH is high. It tends to stick together and make the water cloudy. 

The calcium can also combine with other particulate to form scales on the pool’s edge, trapping dirt and turning black. It can even clog up the pool filter, making it less effective. 


High pH makes chlorine less effective, so you’ll need to use more chlorine to keep the water clean.

Why is pH Important for Your Pool?

Chlorine Effectiveness:

The pH level affects how well chlorine works. If the water is too basic or alkaline, chlorine becomes less effective. 


This means you’ll have to spend more money on chlorine, and your water may not be as clean as it should be.

Equipment Care:

Maintaining the correct pH prevents corrosion of essential pool equipment, including heaters and pumps, ensuring their extended functionality. 

Corrosion Concerns:

Low pH levels can lead to corrosion of pool equipment, like ladders, slides, and diving board supports. In gunite pools, acidic water can even corrode the plaster.

Skin and Eye Comfort:

Water with either low or high pH can irritate your eyes and nasal passages, causing discomfort. Our bodies naturally have a pH close to neutral, so extreme pH levels can strip the skin’s natural oils, making it dry and itchy, and leave your hair dry and brittle.

Clarity of Water:

Off-balanced pH can result in mineral precipitation, leading to cloudy water. This impacts both aesthetics and the quality of the swimming environment.

How do you check and adjust your pool's pH level?


Choose a spot away from the skimmer and return to your pool. Dip a test strip about 18 inches underwater for about 10 seconds. 


When you take it out, avoid shaking off excess water. Wait for the colours on the strip to appear and compare them to the colour range on the test strip container.


Depending on the test results, you may need to adjust the pH of your pool water, especially if you’re concerned about swimming pool temperature. You can do this by following the instructions on the product’s packaging, or you can contact for professional service.


To adjust pH, you’ll use pH increasers (bases) or pH decreasers (acids). The amount you need will depend on how imbalanced your water is and the size of your pool.


Balancing your fiberglass pool’s water chemistry is crucial for pool maintenance. pH level is a key part of this balance. 


It can be affected by various factors, but with some practice and regular checks, you can keep your water in the right range for your pool equipment to work well and for your pool guests to enjoy.

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