What Happens When Alkalinity is Too Low?

Maintaining a swimming pool isn’t just about keeping the water clean and free from debris. Often, the most important elements of your pool are those hidden from sight, such as the chemistry composition of the water for the pool to function properly. 

A crucial element of this is alkalinity. Alkalinity is the measurement of the water’s ability to resist changes in pH levels. When it is too low, it can lead to numerous problems and consequences that can be detrimental to the pool and the health of swimmers. As a pool owner, you need to know both how to reduce alkalinity in a pool and how quickly you can raise alkalinity in a pool.

What Is Alkalinity?

Alkalinity in the water helps to prevent rapid changes in the pH of the pool water. When acidic chemicals are used, they must be neutralized, and alkalinity is needed for this to be possible. If alkalinity is too low, the pH balance of the pool will suffer and this can result in drastic changes in pH. High pH levels can cause corrosion to the pool’s infrastructure, cloudiness in the water, and potentially harm the health of swimmers.

Problems With Low Alkalinity

How do you know if your alkalinity is low? If the alkalinity in a pool is too low, it will cause the pH levels to drop. In other words, the pool’s water is more ‘acidic’ than it should be. Small drops in pH levels might not cause immediate or serious effects, but if unmonitored, it can lead to many problems. These problems may include any or all of the following:


Swimming in a pool with high levels of acidity can cause irritation on the skin and in the eyes. If you suspect your alkalinity levels have dropped, refrain from using the pool until the chemical balance is restored. 


Low alkalinity can cause corrosion in the pool’s equipment, including ladders, pumps, and filters. This can be expensive to repair and can drastically reduce the lifespan of your equipment.


Low alkalinity can also cause the pool’s surfaces to stain. This is because low alkalinity can cause metal parts in the pool’s equipment to rust, leading to stains on the surface of the pool. Once these stains are present, it requires an expensive stain removal process or even a complete refurbishment of all or some areas of the pool’s surface.

Resistance to Sanitizers

Low alkalinity can reduce the effectiveness of chlorine and other sanitizers, which are a very important factor when it comes to maintaining a safe pool environment. A pool without sufficient sanitation methods in place can create an unsafe swimming environment for users.

How to Restore Alkalinity

Luckily, there are many things you can do to restore your pool’s alkaline levels.

Sodium Bicarbonate

Sodium bicarbonate, or baking soda, is an excellent method that can be used to raise the alkalinity level of your pool. To increase the alkalinity by ten parts per million (PPM), you should add 1.4 pounds of baking soda per 10,000 gallons of water.

Alkalinity Increaser

An alkalinity increaser is a product that is designed to raise the alkalinity level in a pool. These products are relatively easy to use and don’t require a great deal of preparation.


Increasing aeration is another way to raise alkalinity levels in a pool. The most common ways to aerate a pool are by running the pool’s fountain or spray jets to get more air into the water. We don’t recommend this method for larger pools, as it is time-consuming and costly.

Replace the Water

When low alkalinity has been overlooked and has severely low levels, you might need to completely refill the pool with fresh water.

Moving Forward

Maintaining the alkalinity level in a swimming pool is essential in order to avoid the problems mentioned in this article. While there are fixes to problems, we always recommend continual, effective maintenance of your pool. It’s easier and more cost-effective to prevent issues early on than try to remedy long-term negligence. Contact us with any issues related to the proper maintenance of your pool, and we’ll do all we can to assist you!

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