How Long Does It Take for Alkalinity to Drop?

One of the critical factors that pool owners need to continually monitor is the alkalinity of the pool water. The ideal range of alkalinity in a pool is between eighty and 120 parts per million (PPM). However, it is not uncommon to experience fluctuations in the alkalinity levels over time. This article will explore some of the common causes of alkalinity drops in a pool and ways to prevent and address this issue when it arises.

What Is Alkalinity?

Before delving into the causes of alkalinity drops, let’s break down what alkaline levels are. Alkalinity is a measure of the water’s ability to neutralize acids. It is primarily caused by bicarbonate, carbonate, and hydroxyl ions, which are present to prevent pH from fluctuating excessively. Understanding this is key when it comes to knowing how to decrease alkalinity in a pool and vice versa. 

Alkalinity levels that are too low or high can result in imbalanced pH levels that can damage pool equipment, irritate swimmers’ eyes and skin and cause algae growth. The ideal pH for swimming pools should be between 7.2 and 7.6 in order to prevent the aforementioned problems from occurring in your pool.

Causes and Consequences of Alkalinity Rises

How quickly can you raise alkalinity in a pool, or how fast can it happen naturally? Here are some key reasons your alkaline levels may be off in your pool:

  • Hard pool water
  • Excessive use of chemicals
  • Accumulation of debris, like leaves and organic sediment
  • Extreme weather

High alkalinity levels can lead to several problems in a pool, including cloudy water, scaling on pool surfaces and equipment, and reduced effectiveness of pool chemicals, including chlorine. High alkalinity levels can also cause pH imbalance, which can result in a burning sensation in your eyes and nose.

How Long Does It Take To Decrease Alkalinity?

There are several factors impacting your ability to decrease your pool’s alkaline levels. The original level of alkalinity, water flow rate, and temperature will all play a part in the time it can take to bring alkalinity levels down. It could take a few days, other times several weeks depending on the levels reached. What causes alkalinity to drop in a pool? Below, we detail ways to lower your alkaline levels and how long the process can take:

Hydrochloric Acid Cleanse

This method involves adding hydrochloric acid to the pool water to lower pH levels and alkalinity. This is a relatively quick method of lowering alkalinity levels, and can take less than a day to complete, depending on how effectively the pool is rinsed and drained.

Muriatic Acid

Adding muriatic acid to the pool water is a common and safe method to lower alkalinity levels. Muriatic acid lowers pH levels and reduces the amount of alkalinity in the water. This is a lengthier solution than others on this list, as it needs to be repeated several times.

Water Replacement 

If alkalinity levels are too high, replacing a significant portion of the pool water with freshwater can reduce alkalinity levels. This is a very effective method, however it is labor-intensive and therefore can be costly and time consuming. If carried out correctly, this can be a relatively quick option.


Increasing aeration or circulation of the pool water can help reduce alkalinity levels over time. Aeration adds dissolved oxygen to the water, which lowers pH levels in order to reduce alkalinity. This is a longer term method, and serves as both prevention and cure.

To Summarize

Maintaining balanced alkaline levels is essential for all pools. It directly affects the health and hygiene of the pool and the swimmers. It’s important to understand the causes of alkalinity buildup and the consequences of high alkalinity, so you can take preventive measures and return your pool back to balanced chemical levels!

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