Most pool owners have experienced low levels of alkalinity in their pool. But what if the pH is already at the right level. Can you increase the alkalinity of the pool without raising the pH?
To raise swimming pool water alkalinity without raising the pH, add 1.5 lbs (680 g) of baking soda (Sodium Bicarbonate) for every 10,000 gallons (37,854 L) of pool water. This will raise alkalinity by 10 ppm. Other names for baking soda include sodium hydrogen carbonate and bicarbonate of soda. It’s often sold in pool stores as Alkalinity Up, Alkalinity Increaser, and pH Buffer.
What is Total Alkalinity?
Total alkalinity is the ability of your pool to resist changes in pH. When chemicals such as chlorine are added to your pool, total alkalinity prevents pool pH levels from going too high or low. In other words, total alkalinity helps stabilize the pH levels and if alkalinity is too low, you will need to raise it.
It is important to remember that pool alkalinity and pool pH are closely related. Under normal circumstances, a rise in alkalinity will be accompanied by a rise in pH, while lowering alkalinity will also lower the pH.
However, as we see below, you are able to raise the alkalinity without increasing the pH.
Keep alkalinity 80 ppm to 120 ppm and pH 7.2 – 7.8
Pool alkalinity is measured in parts per million or ppm. It must be kept between 80 ppm to 120 ppm, while your pool pH range is 7.2 – 7.8.
What Causes Low Alkalinity Levels?
It is normal for a drop in pool alkalinity to occur from time to time. It is mainly caused by rain, diluting the water. Also, acid rain can have an impact. Swimmers and the weather can also affect alkalinity.
There are man-made causes of low pool alkalinity, as outlined:
- Using too many chlorine tablets
- Excessive pool shocking
- Using excessive muriatic acid and other pH reducers to treat pool water
- Draining or backwashing. The water gets diluted when you top up the pool with fresh water which decreases alkalinity.
If you are using muriatic acid to treat your pool, use only the prescribed amount to avoid lowering the alkalinity of your pool. Test your pool after 6 hours to determine if you need to use more muriatic acid before adding it to the pool.
Why You Should Not Raise Pool pH when Raising Alkalinity
Alkalinity and pH levels are closely related. Raising the alkalinity of the pool can lead to an increase in the pH of the pool, which can be OK if your pH was low to start with.
But if your pH level was already around 7.4 or 7.6, then you could have a problem.
If your pool’s pH is higher than 7.8 this will impact the ability of chlorine to kill germs and affect the swimming experience of users. As well as a bunch of other problems.
Problems of increased pool pH:
- Skin irritation or rashes
- Cloudy pool water
- Potential bacterial and viral infections
- Ineffective chlorine
- Scaling of pool equipment leads to expensive repairs
- Restricted pool circulation due to scaling buildup in pipes
So if your pH level is already correct, but the alkalinity is low, it’s important to choose the correct chemical to increase or raise the alkalinity but keep the pH more or less the same.
Pool Chemicals to Raise Alkalinity without Raising pH
The best and safest way to raise your pool alkalinity without raising the pH is by using sodium bicarbonate or baking soda.
Baking Soda (Sodium Bicarbonate) Raises Alkalinity without Raising pH
Products marketed for pools such as Alkalinity Up, pH Buffer, or Alkalinity Increaser are almost always 100% baking soda. Household baking soda can be used too. It’s the same thing as pool baking soda except it’s normally cheaper and readily available.
Baking soda’s chemical formula is NaHCO3 and is comprised of sodium and bicarbonate. It’s sold as a fine white powder for both swimming pool use and home use.
Benefits of Baking Soda for Raising Alkalinity
Baking soda is a very useful and proven substance for controlling pool alkalinity.
- Highly effective at raising pool alkalinity
- It is very affordable
- Readily available in the market
- pH is minimally affected (in other words, it doesn’t really raise pH)
Does Baking Soda (Sodium Bicarbonate) Raise pH?
Perhaps you’re worried that if you use baking soda to raise the alkalinity, it will raise the pH as well? Baking soda does predominantly raise the alkalinity with minimal effect on the pH. The pH may increase slightly, but not like pH-increasing chemicals.
Generally, there are two chemicals that are used to increase pH and alkalinity. They are:
- Soda Ash (sodium carbonate)
- Baking Soda (sodium bicarbonate)
Soda Ash is best suited to make large increases in pH and to increase alkalinity at the same time.
Baking soda, on the other hand, is the best pool chemical to increase the alkalinity without really increasing the pH. To offset any small rise in pH, you can add a little muriatic acid or sodium bisulfate.
How to Raise Pool Alkalinity without Raising pH
This process for raising alkalinity without raising pH is the same for an above-ground pool and an in-ground pool.
To raise alkalinity, you will need the following:
Using Baking Soda to Increase Alkalinity But Not pH
Follow these steps to raise your pool alkalinity using baking soda:
Step 1: Test the Alkalinity
Determine the total alkalinity of your pool using testing strips or a pool water testing kit. The normal range should be between 80 ppm and 120 ppm. If it is below 80 ppm, then you need to raise the alkalinity.
Step 2: Calculate the Amount of Baking Soda to Raise Alkalinity
Calculate the amount of baking soda needed for your pool. You will require 1.5 lbs (680.4 g) of baking soda to raise alkalinity by 10 ppm for every 10,000 gallons (37,854 L) of water in your pool.
Step 3: Mix & Add Baking Soda
Add just a ¼ or ½ of the amount determined in step 2.
The reason we don’t add all of the baking soda is we don’t want to overshoot and raise the alkalinity too high. Mix the baking soda and let it dissolve circulate in the pool for about 6 hours. Run the pool pump throughout the process for complete mixing.
|Baking Soda||Pool Volume (Gallons)|
|0.75 lbs (340 g)||5,000 (18,927 L)|
|1.5 lbs (680 g)||10,000 (37,854 L)|
|2.25 lbs (1,020 g)||15,000 (56,781 L)|
|3 lbs (1,361 g)||20,000 (75,708 L)|
|3.75 lbs (1,701 g)||25,000 (94,635 L)|
|4.5 lbs (2,041 g)||30,000 (113,562 L)|
|5.25 lbs (2,381 g)||35,000 (132,489 L)|
|6 lbs (2,722 g)||40,000 (151,416 L)|
|6.75 lbs (3,062 g)||45,000 (170,343 L)|
Step 4: Retest the Alkalinity & pH
Grab your test kit again and check that both the alkalinity and pH levels are within recommended limits.
If the alkalinity is too low, add more baking soda. If the pH is too high, add some muriatic acid or sodium bisulfate.
Step 5: Test Again
Keep testing the pool alkalinity and pH levels every 24 and 48 hours making small chemicals adjustments at a time to ensure optimum levels.
How to Use Soda Ash to Raise Alkalinity
If you cannot use baking soda for whatever reason, then sodium carbonate or soda ash is a good alternative to raise the alkalinity. Soda ash, however, will increase the pH.
Follow these steps:
Step 1: Test the Alkalinity
Determine your pool’s alkalinity and pH levels using testing strips or a pool testing kit. A drop test kit is much more accurate than test strips.
Alkalinity should be between 80 ppm and 120 ppm.
Step 2: Calculate the Amount of Soda Ash to Raise Alkalinity
Add 10-20 oz (283.5-567 g) of soda ash to raise alkalinity by 10 ppm for every 10,000 gallons (37,854 L) of water.
Step 3: Mix & Add Soda Ash
Don’t add all of the soda ash. Instead, only add ¼ or ½ of what you think you need. It’s better to increase the alkalinity in small increments to avoid overshooting.
Step 4: Retest the Alkalinity & pH
Retest the water to check the alkalinity and pH levels and add more soda ash if needed. Test the pool after 24 and 48 hours to ensure optimum alkalinity levels.
Note: Soda ash will raise your pool’s pH by a large amount compared to baking soda. It is, therefore, preferable, when trying to raise alkalinity without raising pH, to use baking soda if possible. In all cases, use a very reliable testing kit to prevent errors in measuring the alkalinity and pH levels.
How to Use Alkalinity Up or Alkalinity Increaser
These products are specially made for pools. However, they contain they are more or less identical to normal baking soda. Sometimes they add additional ingredients. Essentially, it’s the same thing. However, it is more expensive than baking soda, so it makes better sense to use the latter.
These products should be used exactly like the baking soda above. Add the product incrementally and keep retesting to ensure you do not exceed recommended alkalinity and pH levels.
How Do I Raise Alkalinity in a Saltwater Pool?
Saltwater pools have stable alkalinity of about 70 ppm and a pH of 7.2 to 7.6. If the alkalinity goes below these levels, add baking soda to increase the alkalinity. It works the same as adding to a regular chlorine-based pool.
What To Do If pH Or Alkalinity Levels Goes Too High
Avoid the temptation of saving time by trying to make large alkalinity increases at a time. Instead, add small amounts of baking soda incrementally to avoid overshooting the recommended alkalinity levels. It can be difficult to correct alkalinity if you’ve overshot it by a lot.
If your alkalinity or pH is too high, add muriatic acid or sodium bisulfate. These two products will lower both the pH and the alkalinity.
There are also pH reducers available in the market that you can use for the same purpose.
Tips for Preventing Low Alkalinity in Your Pool
Follow these tips to prevent the alkalinity of your pool from falling below the recommended levels. It will save you the complications of re-balancing your pool’s alkalinity all the time. Remember, the fewer chemicals you add to your pool, the better!
- Avoid draining the pool too often
- Check alkalinity levels every week to detect and adjust levels
- Be careful when using pH reducers such as muriatic acid
- Take care when measuring chemicals, it’s a big cause of incorrect water balance.