With summer on the way, keeping your pool in good condition for swimming will be high on your priority list. Once the Florida summer sun is back in full swing, being able to cool down after a long day will be very relaxing.
Balancing the pH of your pool is an important part of keeping the water sparkling. Without the proper pH balance, numerous problems can arise, which can cause swimming in your pool to become an unpleasant experience rather than a fun way to unwind.
Pool Alkalinity and pH
Total alkalinity and pH are two distinct terms describing different properties. However, the two are often confused for meaning the same thing. This is because the pH scale describes pH levels on the higher end as being alkaline, which sounds similar to alkalinity, and while the two are related, they’re measured separately.
To understand the difference, a basic understanding of the pH scale vs alkalinity is required (no pun intended).
What is the pH Scale?
The pH scale is measured in values ranging anywhere from 1 to 14. This measurement system is based on the pH value of pure water – so perfectly pure water is right in the middle of the scale, measuring a pH value of 7.
A substance measuring with a pH of 7, or approximately 7, it’s considered to be neutral.
Water measuring on the lower end of to pH scale – which is anywhere under 7 – is described as being acidic, while water samples measuring more than 7 are considered to be basic or alkaline (these are two interchangeable terms describing a pH of more than 7).
The term pH is short for “power of hydrogen”. That’s because the acidic of basic properties of substances is determined by the amount of hydrogen ions in a solution:
- A higher concentration of hydrogen ions results in a lower, or more acidic pH
- A lower concentration results in a high, more alkaline pH
To simplify this, simply remember that the concentration of hydrogen ions and the pH value of a substance will have an opposite effect. As one goes up, the other goes down, and vice versa.
Measurements in the pH scale are, in fact, logarithmic. What this means that the difference between every whole number in the pH scale actually represents a pH value of ten times that of the previous number. Here’s how it works:
- A pH of 6 is 10 times more acidic than a neutral pH of 7
- A pH of 8 would be 10 times more basic than a neutral pH of 7
- A pH of 9, is 100 times more basic than pure water, seeing as it’s 10 times more basic than 8 and 8 is 10 times more basic than 7 and 10 x 10 = 100
The logarithmic nature of the pH scale is the reason why even small variations in the pH value of a substance, actually represent large changes in its overall acidity or baseness.
As an example of how big a difference a small variation in pH can make – blood in the human body can have a pH ranging between 7.35 to 7.45, which is slightly basic. Although generally the pH should be around 7.4.
While the pH of urine can vary from 4.5 all the way up to 8, a person would die if their blood pH levels dropped below 7. So there’s a very minimal range of pH levels able to support life, as even small variances in pH values, represent large difference in how acidic or basic a substance is.
With regards to your pool, this demonstrates how important it is to balance the pH of your pool water and how even a single number value lower or higher than what’s ideally recommended, can make a big difference to the quality of your water.
What is Total Alkalinity?
Unlike pH, which measures the acidic or basic properties of water based on the concentration of hydrogen ions, total alkalinity simply measures the amount of basic substances dissolved in water. Instead of being measured using the pH scale, total alkalinity is measured in parts per million (or ppm for short).
For pool water, the ideal total alkalinity can differ, but it ranges between 80-120ppm and will depend on what chlorine you use, which will be covered in more detail later.
With more alkaline substances dissolved in the water, acidic substances will be neutralized, so an ideal total alkalinity will help pool water be resistant to becoming overly acidic. If you don’t maintain a good level of total alkalinity for your pool, you’re likely to find that the pH will always be fluctuating.
So while total alkalinity and pH aren’t the same thing and they aren’t measured using the same system, they are related, as a higher total alkalinity will tend to either increase or stabilize the pH of your pool.
Why a pH Imbalance is Harmful
Just like small pH imbalances can wreak havoc on the human body, small differences in pH values can have a big impact on your pool. It doesn’t matter whether the imbalance is towards to more acidic or basic end of the pH scale, as any imbalance is potentially harmful.
Eye and Skin Irritation
Seeing as the human body has a natural pH of around 7.4, a pool pH imbalance can cause issues. A pH imbalance can cause irritation of the eyes and skin, as well as leaving hair brittle and skin itchy and dry after taking a swim.
Imbalanced pool pH can lead to damage of the pool vinyl liners, as well as causing corrosion of pumps and other mechanical systems. Having a consistently imbalanced pool pH will take its toll on the longevity of your pool and cost a lot of money in pool maintenance and repairs.
A pH imbalance will affect the efficacy of the chlorine you use to clean your pool. If the pH is too low, chlorine will dissipate quickly, with no long-lasting effects. Because of this, it will take a lot of chlorine to maintain pool sanitation, much more than you’d normally expect.
On the opposite extreme, a pH that’s too high will make chlorine ineffective, inhibiting the ability of chlorine to kill off bacteria, mold and other undesirable micro-organisms.
In both cases, a pH imbalance will result in difficulty maintaining a sanitary pool. The result will be mold growth and a high bacteria count. In the case of acidic water, this would be because of chlorine dissipating too soon, while in in the case of basic water, the chlorine will remain in the water, but won’t kill off bacteria.
The Ideal pH for Your Pool
The acceptable pH range for a pool is anywhere between 7.2-7.8, which is rather close to neutral and similar to the pH of the human body. However, it’s best to narrow down the pH fluctuation of your pool water so it always measures between 7.4-7.6, as this is the most ideal pH to maintain and will avoid irritation of the skin and eyes.
To maintain an acceptable pH, a combination of products can be used:
- Products containing sodium bicarbonate or sodium carbonate will raise the total alkalinity of pool water
- Carbon dioxide can be used to lower water pH
- Acid can be used to lower both pH and total alkalinity
To know whether pool water is too acidic or basic, it’s best to regularly test the pH of your pool. However, it’s useful to know that water that’s too basic is likely to have a cloudy appearance, as this can help you identify pool water that’s too basic more easily.
How to Fix Corrosive or Scale-Forming Water
A lot of people falsely believe that maintaining the right pH balance is the only factor to consider when managing the corrosive or scale-forming properties of pool water.
While pH does play a factor, the Langlier Saturation Index (or LSI for short) is one of the most important factors to consider if you’re struggling with corrosive or scale-forming pool water.
To simplify the LSI, it can be seen as a measurement system to establish whether water will have corrosive or scale-forming tendencies. When water isn’t saturated enough, it will be corrosive and will “eat into” your pool to obtain enough calcium and other solvents. If water is too saturated, it will deposit calcium and other minerals to obtain the right balance, making it scale-forming.
The ideal LSI measurement is 0.0. If the LSI is too low (anywhere below 0.0), water will be undersaturated and have corrosive tendencies. If the Langlier Saturation Index is too high (a positive figure above 0.0), water will be over-saturated and will be scale-forming, which means that you’ll struggle with lime deposits.
Maintaining the perfect pool for the summer might seem complicated, but it doesn’t have to be. By learning more about your pool water and different products, keeping your pool clean maintained for the summer will be almost effortless.
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