Raising Alkalinity without Raising pH in a Pool




Maintaining the right balance of chemicals in your pool is essential for keeping the water clear and safe for swimming.

One important factor to consider is alkalinity, which helps to stabilize the pH levels in your pool.

However, some pool treatments can raise pool alkalinity levels while also raising the pH, creating an imbalance in the water. In this article, we’ll show you how to raise alkalinity without raising the pH in your pool (well at least by as little as possible).

How to Raise Alkalinity without Raising pH

How to increase alkalinity?

To increase the alkalinity in a pool, without raising the pH too much, follow these steps:

Test the water

To check your water we recommend that you get a proper water testing kit (either a liquid test kit or test strips) which can give you a wealth of information regarding the state of the water in the pool.

The ideal range for alkalinity is between 80 to 120 ppm (parts per million).

Recommended Test Strips

AquaChek 7-Way Pool and Spa Test Strips - Silver Pool Test Strips For pH, Total Chlorine, Free Chlorine, Bromine, Alkalinity, Total Hardness, and Cyanuric Acid - Water Quality Testing Kit (100 Strips)

Aquachek 7-way test strips

I use these test strips that can tell you the total chlorine/bromine, free chlorine, pH, total alkalinity, CYA and hardness levels.

Calculate how much baking soda to add

Based on the size of the pool and the difference between the current alkalinity level and the desired level, calculate how much alkalinity increaser you need to add.

Generally, a good rule of thumb to follow in this regard is to add 1.5 lbs of baking soda for every 10,000 gallons of water to increase the alkalinity by roughly ten parts per million (also called ppm). 

Alkalinity ReadingBaking soda to add per 10,000 gallons
100ppm or above Do not add any
Baking soda pool calculator/chart

The table above gives a guide to the number of pounds of baking soda to use to raise the alkalinity in your pool. You will need to know the volume of water in your pool of course – if you are not sure then it can be quite easy to calculate.

You can either buy baking soda in bulk from a supermarket or you can buy Alkalinity Up (baking soda) on Amazon.

Doheny's Alkalinity Up, Alkalinity Increaser for Swimming Pools, 25 Pounds

Add the baking soda

Mix the baking soda in a bucket of pool water and stir until most has dissolved. If you need to add quite a bit then you will need to do this several times as there is a limit as to how much you can dissolve in a bucket of water.

Walk around the pool, pouring the alkalinity increaser into the pool. You should have the pool pump running. Distribute the product evenly around the pool. Avoid adding it directly to the skimmer or in a concentrated area.

Circulate the water

Run the pump for at least two hours to circulate the water and allow the baking soda to evenly distribute throughout the pool.

Test the water again

After adding the product and running the pump, retest the water to confirm that the alkalinity levels have increased. If not, repeat the process.

What is the difference between alkalinity and pH?

Alkalinity and pH are two important parameters in the management of pool water chemistry.

Total Alkalinity in a swimming pool refers to the amount of alkaline substances present in the water which have the ability to neutralize acids. It is expressed in milligrams per liter (mg/L) of calcium carbonate (CaCO3). Total alkalinity acts as a buffer to prevent drastic changes in pH levels.

A pool with proper total alkalinity will have a pH level that stays within a stable ideal range which in a pool is between 80 to 120 mg/L.

pH refers to the measure of acidity or the basicity of water. It is expressed on a scale of 0 to 14, with 7 being neutral. The ideal range of pH in a pool is between 7.2 to 7.8.

Why raise alkalinity?

Alkalinity acts as a buffer in the pool, preventing large changes in pH levels and helping to keep the water stable. When alkalinity levels are too low, the pH levels in the pool can become too acidic, which can cause damage to the pool’s surfaces and equipment and cause skin irritation and eye irritation for swimmers.

In addition to its role in maintaining pH stability, alkalinity also affects the ability of chlorine to kill harmful bacteria and other pathogens in the water.

  • Low alkalinity levels can often prevent chlorine from being effective, which can lead to an increased risk of waterborne illnesses.
  • High alkalinity levels, on the other hand, can make chlorine less effective, meaning that higher levels of chlorine are needed to maintain a safe and healthy pool environment.

So, why is it important to raise the alkalinity in a pool? Simply put, it helps to keep the water safe, clear, and comfortable for swimming. By maintaining the right levels of alkalinity, you can help to prevent skin irritation, eye irritation, and other health problems, as well as protect your pool’s surfaces and equipment from damage.

Why avoid raising the pH?

Although raising the alkalinity in a pool is important for maintaining the chemical balance of the water, raising the pH levels too high can have unintended consequences.

A pH level that is too high can cause the water in the pool to become overly alkaline, which can have a number of negative effects.

  • High pH levels can cause the water in the pool to become cloudy, making it difficult to see through the water and reducing the overall aesthetic appeal of the pool.
  • High pH levels can cause scale buildup on the waterline of the pool and on its equipment, leading to decreased efficiency and increased maintenance costs.
  • High pH levels can make chlorine less effective at killing harmful bacteria and other pathogens in the water. This can increase the risk of waterborne illnesses and other health problems, making the water in the pool unsafe for swimming.
  • High pH levels can also lead to skin and eye irritation for swimmers. The high alkalinity levels can cause the water to feel rough and harsh on the skin, and can also lead to burning, itching, and redness in the eyes.

The difference between baking soda and soda ash

Both baking soda and soda ash can be used to raise the alkalinity levels in a pool. However, if you use soda ash it will raise the pH much quicker and to a higher level.

Although baking soda will increase the total alkalinity of a pool, it takes a larger quantity to raise the pH compared to soda ash. Also, baking soda has a pH of around 8-8.3 so it is not strongly alkaline – just slightly above neutral. No matter how much you add the pH will not go above this.

Soda ash (sodium carbonate) raises the pH in a pool more quickly than baking soda (sodium bicarbonate) because it is a stronger base (around 11.5) and therefore, a smaller quantity will have a greater impact on the pH level.

Read: What does baking soda do to a pool

Does raising alkalinity also raise pH?

By adding either baking soda or soda ash you may also increase pH if it is low. Baking soda will raise the pH slower than adding soda ash.

Can you swim in a pool with low alkalinity?

Swimming in a pool with low alkalinity is not recommended as the chlorine in the pool may not be able to sanitize the water properly and the water may be too acidic.

What if alkalinity is low but pH is high?

If the total alkalinity is low but the pH is above 6.8 then you should add baking soda (sodium bicarbonate) which will increase the total alkalinity without raising the pH.

Does rain increase alkalinity in pool?

Rain is normally slightly acidic so it will actually decrease the alkalinity in a pool rather than increase it. You may need to use baking soda or soda ash to increase the alkalinity after rain (but not always).

What happens if alkalinity is too low in pool?

If the alkalinity is very low then the chlorine in the pool will not be much less effective at sanitizing the water which could lead to problems for swimmers.

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