Chemistry may not be the most exciting topic in the world, but as a pool owner, you need to understand the basics of pH and alkalinity. Pool alkalinity levels are crucial in your overall pool chemistry and in keeping your swimming pool clean.
So, below I cover everything you should know about total alkalinity and some helpful tips on adjusting your levels.
- Alkalinity is water’s ability to neutralize acids and bases and stay at a constant pH level.
- Balancing your pH level is a crucial step in keeping your pool clean and safe.
- Many things can affect your pool’s alkalinity, like rain, sweat, and other contaminants.
- You can raise total alkalinity with baking soda, and lower total alkalinity with sodium bisulfate or muriatic acid.
What Is Pool Alkalinity?
Pool alkalinity describes water’s ability to neutralize acids and bases. Said another way, it denotes how water can hold up against sudden pH changes. Maintaining total alkalinity and pH is crucial for keeping your pool safe for swimmers.
PH is a scale that indicates how acidic or basic (alkaline) water is, based on the concentration of hydrogen ions.
The pH scale ranges from zero to 14, where seven is neutral. Most pool owners know that maintaining a neutral pH level is a balancing act. If your pool’s pH level is less than seven, it’s too acidic, and a pH of more than seven is too alkaline.
So when you measure pH, you’re assessing how acidic or alkaline your pool water is, based on the substances within the water. If your pool water’s pH level is low, likely, its alkalinity is also low. And the opposite is true: if the water’s pH is high, its alkalinity will almost certainly be high as well.
Here are a few examples of common acidic and alkaline substances for reference.
- Lemon juice has a pH level of approximately 2.0 to 2.5 (highly acidic)
- Most coffees have a pH ranging from 4.85 to 5.1 (acidic)
- Drinking water has a pH level ranging from 6.5 to 8.5 (neutral)
- Ammonia has a pH of approximately 11.6 (moderately alkaline or basic)
- Bleach is a corrosive cleaning product due to its pH between 11 and 13 (highly alkaline)
pH vs. Total Alkalinity
It’s important to note that pH and total alkalinity are not the same thing. You don’t use the pH scale from 0 to 14 to measure alkalinity. Rather, total alkalinity is measured in parts per million (ppm). I discuss more on total alkalinity measurement below.
Why is Pool Alkalinity Important?
Acidic water can cause eye, nasal, and skin irritation and corrode your pool equipment and plumbing. In contrast, if the water is too alkaline, it may cause scaling on the pool’s plumbing and surface, as well as cloudy or murky water.
Furthermore, low or high alkalinity negatively impacts chlorine, the most frequently used chemical to keep your pool water free from potentially dangerous bacteria. Chlorine cleans pools by attacking the fats known as lipids in cellular walls in bacteria and other microorganisms, harming their intracellular structures and enzymes and killing them (See below for more information on chlorine).
So what is the ideal pH level for your pool water? You’ll want to aim for 7.4 to 7.6 on the pH scale. Slightly alkaline water will be the kindest to your pool and your skin, eyes, and nose since this pH level enables chlorine to work its magic best.
What Is The Right Amount Of Alkalinity?
The ideal range of total alkalinity for your pool is 80-120 parts per million, depending on the type of chlorine you use. You can use a swimming pool testing kit to measure the alkalinity of your pool.
Here are the other chemical levels you should aim for in your swimming pool.
What Happens If Pool Alkalinity Is Too Low?
If you do not test the water regularly, acidic water may go unnoticed and cause the alkalinity to decrease. Low alkalinity can lead to the following:
- Irritated eyes and dry, itchy skin
- Corrosion of the pool’s metal surfaces, including pipes, screws, and filters
- Staining of your pool’s walls/lining
- pH bounce, meaning quick fluctuation in the pool water’s pH levels
- Cracking and pitting of your pool walls/lining and surfaces
- Decreased effectiveness of chlorine and other pool sanitizers
What Happens If Pool Alkalinity Is Too High?
High alkalinity is not as damaging as low alkalinity. However, keeping your pool’s total alkalinity balanced is still crucial. Doing so will help prolong the life of your pool’s filters, pump, and pipes and lower your maintenance costs. High alkalinity and an imbalanced pH level may cause the following:
- High pH and reduced chlorine effectiveness
- Reduced water circulation due to clogged pool filters, pipes, circulation equipment, and heaters
- Water scaling and calcium buildup on pool equipment and surfaces
- Cloudy, murky water
- Increased water pressure secondary to pipes narrowing and becoming clogged, causing them to work harder, which may result in cracking and the need to replace your pool pump
- Irritated eyes and nasal passages, as well as itchy skin
Low alkalinity will prevent sufficient removal of viruses, bacteria, algae, and other microorganisms, putting swimmers at risk. Your pool water will also become corrosive, causing damage to your pool’s surfaces and equipment.
What Causes Alkalinity Levels to Increase?
Many factors can cause your pH or alkalinity levels to go up or down. When your pool water’s pH level rises, the alkalinity level will also begin to increase. It can be difficult to balance these levels, so regularly testing the water is important.
Here are some of the causes for an increase in your alkalinity level.
Adding too much sodium bicarbonate: When pool water has a low pH, you add sodium bicarbonate to increase the alkalinity. However, too much sodium bicarbonate will raise the pH too much and unstabilize the alkalinity.
Rainwater: Rainwater diluting the pool water can go both ways. Depending on your region and the pollution levels, rainwater could be slightly acidic or basic. For this reason, it is important to test the water after heavy rain.
Dirty water: Algae is usually slightly basic. So a dirty pool will have high alkalinity.
What Causes Alkalinity Levels to Decrease?
Here are some of the causes for a decrease in your alkalinity level.
Overshocking: Pool owners will often use too much shock or shock the pool too frequently.
Body fluids: Body sweat and urine are generally slightly acidic. So when lots of people have been spending time in the pool, the alkalinity will likely decrease.
Overuse of muriatic acid: Muriatic acid is used to lower the pH level in pools when the alkalinity is too high. But if you do not measure the chemical properly, you will likely bring the alkalinity too low.
How Can You Adjust the Alkalinity In Your Pool?
Begin by determining how many gallons your pool holds and the specific ppm level you’d like to obtain. As noted above, the appropriate range is between 80 and 120 ppm. If you don’t know how many gallons of water your pool contains, you can use my pool volume calculator to confirm your pool’s size.
How to Raise Alkalinity
If you need to raise your pool’s total alkalinity, use baking soda (also called sodium bicarbonate) or any alkalinity-increasing product. However, if you choose to use the latter, ensure that the product is made from sodium bicarbonate since that is the main component that increases pH. After adding the baking soda or alkalinity increaser, let your pool settle for six hours, then retest it.
How to Lower Alkalinity
In contrast, lower your pool’s total alkalinity by using alkalinity-decreaser products, such as sodium bisulfate (also called dry acid) or muriatic acid. After you’ve followed the products’ directions and added the dry acid, muriatic acid, or other alkalinity-decreaser product, check your pool water’s pH level to ensure it’s now in the acceptable range. Check out my article on what is muriatic acid used for in pools for step-by-step instructions on how to use this pool chemical.
I linked my articles above to raise and lower your pool’s alkalinity levels if you want to check those out. You can also use my pool alkalinity calculator to help you out.
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You don’t have to be a chemist to understand alkalinity and keep your pool sparkling clean. Following the suggestions above, your beautiful swimming pool will make your backyard the most popular spot in your neighborhood.
Questions? Let me know.