How to Raise Alkalinity | Pool Alkalinity Low

If you’re wondering how to raise alkalinity in a pool, naturally, you’ve come to the right place. In a step-by-step approach, discover how to tackle low pool alkalinity without using a pool guy!

Low alkalinity relates to a high level of acidity. This acidic environment can become corrosive and unsafe for both your swimming pool and the people swimming. If left untreated for weeks on end, you’ll be left with an un-swimmable pool on your hands, and not to mention an expensive tab to pay in order to fix it. 

In short, you can successfully lower the alkalinity in your pool by adding baking soda, soda ash, or alkalinity up/alkalinity increaser, pH Up products. Follow along to learn more about how these products are used, added, and tested to successfully raise your pool’s alkalinity with ease.  

girl-swimming-in-the-pool
girl swimming in the pool

What is Alkalinity in a Pool?

Alkalinity in a pool is a measurement of the water’s ability to neutralize or resist an acid to maintain a stable pH. Alkalinity is closely related to pH in that when one goes down, the other follows close behind. This is why low alkalinity is associated with a low or acidic pH (below 7.0). 

As alkalinity drops, the water pH is no longer stable. This can result in large fluctuations of the pH with only minor changes in the pool’s chemistry. 

What Causes Low Alkalinity in Pool?

It’s very normal to experience a drop in alkalinity levels in your pool over the season. For the most part, this is due to natural causes such as evaporation or agitation of your water. Throughout the hot summer season, your pool will release dissolved carbon dioxide (CO2) in a process known as ‘water degassing’. This directly impacts total alkalinity, causing it to fall below 80 ppm if left untreated. 

Other causes of low alkalinity include:

  • overuse of alkalinity lowering products (i.e. muriatic acid) 
  • using too many chlorine tablets with low pH 
  • excessive rainwater diluting the pool 
  • draining or backwashing pool water

Effects of Low Alkalinity in Pool

Low alkalinity can be quite damaging to your pool. The acidic pool water can corrode the pool walls and surfaces leading to etching and cracking. Metal surfaces are likely to discolour and eventually dissolve over time. 

Along with the damage to your pool surfaces, low alkalinity will also interfere with the sanitizing activity of chlorine. Without a good disinfectant, your pool will turn into a breeding ground for microorganisms in no time. 

Fortunately, these issues are 100% curable so long as you know what to do!

What Level Should Pool Alkalinity Be?

Your pool’s alkalinity should stay within a range of 80-120 parts per million (ppm). Within this range, it’s unlikely you will experience any fluctuations in your pool’s chemistry. At this alkalinity, you should also maintain a pH range between 7.2-7.6 to avoid damage from acidity. 

How to Raise Alkalinity in a Pool Naturally – Step by Step

When your pool’s alkalinity drops below 80 ppm, you need a safe and effective product to help raise the alkalinity. Let’s take a look at how to adjust alkalinity using 3 natural products. 

Step 1: Pick a product

Product #1: Baking Soda (Sodium Bicarbonate)

Sodium bicarbonate, better known as your household baking soda, is an effective product used to raise the alkalinity in your pool. 

The main purpose of baking soda is to raise alkalinity while only slightly raising pH.

For example, in a 10,000 gallon pool with a pH reading below 7.2, you would require 21 lbs of baking soda to reach optimal pH ranges of 7.2-7.6. However, this amount of product would increase total alkalinity by 150 ppm! It’s important to keep this in mind when using baking soda. 

Product #2: Soda Ash (Sodium Carbonate)

Soda Ash is another pool product that works opposite to baking soda. Soda Ash helps raise the pH in your pool while only slightly raising its alkalinity. 

For example, if your swimming pool needed to raise its pH by 0.5, you would only need 12 ounces of soda ash to do so. At this measurement, it would only increase alkalinity by about 8-10 ppm.

Product #3: Alkalinity Up or Alkalinity Increaser

increase-alkalinity-in-pool-water
alkalinity increaser for pool water

The majority of the ‘Alkalinity Up’ or ‘Alkalinity Increaser’ products contain close to or 100% baking soda in them. Although specialized for pools and hot tubs, regular baking soda is just as effective and often cheaper. 

Step 2: Adding the product 

Product #1: Sodium Bicarbonate (Baking Soda)

The general rule of thumb when adding sodium bicarbonate to your pool is that it takes roughly 1.5 lb to raise alkalinity by 10 ppm in a 10,000 gallon pool. Check out the table below to determine how much baking soda to raise alkalinity in your pool. 

Amount of Sodium Bicarbonate (Baking Soda) to Raise Alkalinity

Pool
Volume
(gal)
>120 ppm Alkalinity80-120 ppm
Alkalinity
70 ppm
Alkalinity
60 ppm
Alkalinity
50 ppm
Alkalinity
1,000Add Muriatic AcidIdeal2.4 oz4.8 oz9.6 oz
5,000Add Muriatic AcidIdeal16 oz24 oz23 oz
10,000Add Muriatic AcidIdeal1.5 lb3 lb6 lb
20,000Add Muriatic AcidIdeal3 lb6 lb9 lb
50,000Add Muriatic AcidIdeal15 lb30 lb60 lb
Chart shows how much baking soda to raise alkalinity in pool
  • After determining the amount of baking soda to add to your pool based on the size and current alkalinity level of your pool, start by adding only ½ or ¾ of that amount.
  • Evenly distribute the powder across the entire pool using gloves and goggles for protection.
  • Let the baking soda circulate and dissolve for 6 hours. Allow the filtration system to continue to run throughout this time. 
  • After 6 hours, you’re ready to move onto step #3 (retesting the water). 

Product #2: Sodium Carbonate (Soda Ash)

The general rule of thumb when adding sodium carbonate to your pool is that it takes roughly 15-20 oz to raise alkalinity 10 ppm in a 10,000 gallon pool. Keep in mind that this will also raise your pH by about 0.5 units. 

  • After determining the amount of baking soda to add to your pool based on the size and current alkalinity and pH of your pool, start by adding only ½ or ¾ of that amount.
  • Evenly distribute the powder throughout the entire pool.
  • Let the soda ash circulate and dissolve for 6 hours. Allow the filtration system to continue to run throughout this time.
  • After this is done, you’re ready to move onto step #3 (retesting the water). 

Product #3: Alkalinity Up or Alkalinity Increaser

How to add alkalinity increaser to your pool?

Any ‘Alkalinity Up’ or ‘Alkalinity Increaser’ products should be used in the same way as baking soda. Refer to product #1: Sodium Bicarbonate (Baking Soda) for directions as to how to add these products to your pool. 

Step 3: Test the alkalinity of your pool 

After adding the product and waiting about 6 hours for it to disperse and dissolve in your swimming pool, it’s time to start testing. Make sure you have a reliable testing kit for both total alkalinity and pH.

You can use pool water testing strips or a liquid water testing kit.

man testing for low alkalinity in swimming pool water
man testing for low alkalinity in swimming pool water

Begin to take readings after 6 hours, then 24 hours, then 48 hours to gauge if there are any small changes over this period and to ensure the chemicals are balanced. Make sure that both the total alkalinity and pH values are within optimal ranges. If so, your job is done!

Step 4: Repeat (if necessary)

If your alkalinity and pH values are slightly lower than expected, that’s ok! You’ll want to add the remaining amount of product that was put aside in the first round of application. Remember, it’s better to add smaller increments to not overshoot the alkalinity and pH in the first few attempts. 

It’s important to note that testing for alkalinity first is far more useful. When the total alkalinity is back up to 80-120ppm it will help to buffer the pH, resulting in less frequent disruptions in pH.

Pool Alkalinity FAQ: 

Is it safe to swim in a pool with low alkalinity?

As mentioned earlier, low alkalinity goes hand in hand with a low pH creating an acidic environment.

As a more dramatic example, you would never want to swim in a bath filled with lemon juice because the acidity would sting your eyes and irritate your skin! For this reason, swimming in a pool with low alkalinity is definitely not recommended. 

How to raise alkalinity in a saltwater pool?

Adjusting the alkalinity in a saltwater pool is relatively similar to that in a chlorine pool. The difference is, saltwater pools are much more stable at an alkalinity of 70-80 ppm and a pH of 7.6. When your saltwater pool dips below 70 ppm, baking soda is a great option to assist in raising the alkalinity.

How to raise alkalinity in an above ground pool?

The process of raising alkalinity in an above ground pool is the same as that for an in-ground pool. The only difference is, well, it’s above ground. You can proceed with the same steps described above to adjust for alkalinity and pH. 

Over to You

Raising your swimming pool’s alkalinity should be a stress-free and simple process. Since arriving at this article, you’ve already accomplished the first step in adjusting your alkalinity: learning how to do it right!

Using natural products can be a safe and effective way to ensure you reach optimal alkalinity and pH levels. Depending on your swimming pool’s chemistry, baking soda and alkalinity increasers are shown to be the most useful in raising alkalinity while soda ash works best to raise the pH. 

We’d love to hear from you! Are there any other natural products that have worked well in raising the alkalinity in your swimming pool? If so, which ones do you recommend?

Recommended Products

Baking Soda

Alkalinity Up or Alkalinity Increaser

Pool Water Testing Strips

Liquid Pool Water Testing Kit

Favorite Pool Products

Chlorine

Pool Brush

Pool Skimmer Rake

Suction Pool Cleaner

Robotic Pool Cleaner

Swimming Pool Cover

Swimming Pool Cover Roller

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