If your reef tank does not have the right amount of alkalinity, that’s not good for the overall health of the inhabitants in the tank. When the alkalinity is low, you need to raise it using several chemicals and commercial premixes. In this article, we are going to share how you can raise alkalinity in the reef tank along with other relevant topics.

To raise alkalinity in the reef tank you can use soda ash, limewater, baking soda, or different commercial premixes available in the aquarium shops. The limit and frequency of using these alkalinity boosters depend on the amount of water, size of the reef tank, and many more.

Apart from discussing the alkalinity boosters in this post, we are also going to talk a bit about alkalinity, why it is important to test alkalinity, and how to test alkalinity in the reef tank. Want to learn about all of these? Relax and keep reading.

What is Alkalinity?

All the bases in the water equal to the total alkalinity. In other words, alkalinity controls the buffering capacity of the water. It is alkalinity that possesses the power to control the pH in the water.

When it comes to the base, carbonate is the most common and important one found in the water. When we want to measure the total alkalinity in surface water, we use mg/L or milligrams per liter approach. Alkalinity can also be measured by parts per million or ppm of calcium carbonate.

However, when it comes to the aquarium industry, the term KH or “carbonate hardness” can be used to refer to total alkalinity. Total alkalinity in the aquarium or reef tank is usually measured in degrees (dKH) instead of ppm or mg/L. Mathematically, 1 dKH is equivalent to 17.9 ppm or 17.9 mg/L.

How to raise alkalinity in reef tank

Complementary Article: How To Lower Alkalinity in a Reef Tank

Why is Alkalinity Important for Reef Tank?

For any kind of saltwater aquariums including reef tank, maintaining the right degree of alkalinity is crucial for a variety of reasons:

  • Be it skeletal formation or coral calcification, it is essential to keep the proper balance of alkalinity (8-12 dKH or 142-215 ppm) in the reef tank.
  • A proper level of alkalinity prevents coral bleaching, pH swings, and tissue loss.
  • It helps to increase the performance of the equipment in the tank.
  • More alkalinity helps to prevent the rapid swings in pH levels.

Why Do We Need Alkalinity Test?

Being introduced by the system, the alkalinity helps to buffer the acids in the tank. In reef tanks, alkalinity can exist in two forms: carbonate and bicarbonate. It is crucial to undergo an alkalinity test regularly for the reef tank as it will help the formation of the skeleton and calcification of corals. Marine organisms might be under threat if the alkalinity test is not performed and the alkalinity level is not regulated.

If you want to bring a balance in the reef tank and want the inhabitants to stay healthy, you should test alkalinity in the water at least once a week.

One rule of thumb is to perform an alkalinity test when you test the pH level in the tank. However, the testing time may vary as per the dosing schedule and the requirement of the tank.

If you have a reef tank, make sure that the tank has the recommended level of alkalinity which is 8-12 dKH or 142-215 ppm.

How to Test Alkalinity in the Reef Tank?

There are two ways to test alkalinity in the reef tanks: using test strips or using test kits. Let’s see how these methods work.

Method 1: Test Alkalinity with Test Strips

If you intend to test the total alkalinity in the reef tank, test strips are the easiest options for you. The method of testing alkalinity with test strips might vary slightly from manufacturer to manufacturer. We recommend you read the instructions given with the test strips carefully before conducting an alkalinity test.

Typically, you take one test strip and then dip a part of it in the reef tank. Keep that submerged for about 10 seconds. Then, keep the strip at rest to let the reagents work with the water of the reef tank. And finally, you will find a color in the test strip hinting to the alkalinity level.

Refer to the color scale of the test strips in the container/manual of the test strips to compare that with the color you find in the real alkalinity test. This test will give an idea about the approximate degree of alkalinity in the test

Note that the real color you get in the test strips might not exactly match with the benchmark colors you see on the color scale provided by the manufacturer. You are advised to use your best judgment to define the real range of total alkalinity.

Method 2: Test Alkalinity with Test Kits

Apart from using test strips, you can also make use of test kits to get the total alkalinity in the reef tank tested. The process of testing alkalinity with the test kits differs slightly from testing with test strips.

First of all, collect some water from the reef tank in the test tube. Mix the reagent to the collected water. Wait for a few minutes to let the reagents mix mixed well with the water and show you the result.

When the process is completed, you’ll see the color indicator showing the result. Match the color with that of the color scale provided by the kit’s manufacturer and try to guess the total alkalinity level in the water.

When it comes to accuracy, test kits are more accurate. However, the accuracy level of the test strips is also enough for judging the level of alkalinity.

5 Simple Ways of Raising Alkalinity in Reef Tank

There are times when you might need to raise the alkalinity in the reef tank to let the animals in the tank grow naturally. It is because when the alkalinity level is too low, the water of the reef tank can go through the pH swings which is very detrimental for marine animals.

Many organisms in the water need a range of alkalinity to live healthy and sound. If the level of the alkalinity goes poor, the growth of those animals gets hampered. Let’s see some of the ways you to raise alkalinity range in the reef tank:

  1. Soda Ash is one of the best solutions to try when you are worried about low alkalinity issue. You can buy soda ash from the aquarium shops or online. Follow the instructions given with the product to raise alkalinity slowly. Too much of Soda ash abruptly can cause tissue loss or coral bleaching.
  2. Sodium bicarbonate or baking soda is another popular choice to raise the alkalinity in the water. However, make sure that you use it in a way so that the alkalinity does not get more than 1.4 dKH a day.
  3. If you want to balance both the calcium and alkalinity, you can use limewater or Kalkwasser.
  4. Calcium carbonate or carbon dioxide reactors also work great to increase the level of alkalinity and calcium.
  5. You can also go for 2-part alkalinity and calcium supplements available commercially such as B-ionic or C-Balance. The more you add these to the reef tank water, the more the alkalinity and the calcium level will go up. However, you can add calcium and alkalinity differently if you intend to do so. In that case, you have to use calcium chloride along with sodium bicarbonate. Just make sure that you have made the right balance.

Important Things to Remember While Increasing Alkalinity in Reef Tank

  1. The manufacturers of the commercial premixes or alkalinity boosters usually recommend the quantity of the products for maintaining the tank, not generally for correcting the imbalances. So, when you are using the commercial products for correcting the low alkalinity issues, you might need to add much solution than you usually add for maintaining a reef tank.
  2. If you intend to use alkalinity and calcium additives separately, you must be careful so that you do not make an imbalance. Do not add one too much compared to the other. You have to make some small experiments to find out the right amount of additives you need to add in the reef tank that helps to keep the animals of the tank healthy.
  3. 1 teaspoon of baking soda per 10g of water will raise the alkalinity level or dKH by 1 point. Add the soda in the flow of fresh saltwater gradually, not abruptly. Increase the amount of baking soda or soda ash slowly to the desired level.
  4. If you cannot attain the desired amount of alkalinity level even after adding a large amount of alkalinity and calcium supplements, you should measure the magnesium level in your reef tank. If the magnesium is very low, the calcium carbonate or alkalinity supplements might not work as expected. So, make sure that the shortage of magnesium is not preventing the alkalinity solutions from being effective.
  5. Do not add too much alkalinity in the water than required. If you do so, the reef tank might lose the balance and organisms will get hampered. Too much calcium carbonate in the reef tank water is responsible for coral bleaching, alkalinity burning, and the low performance of pumps and heaters. Calcium carbonate can also hamper the efficiency of other equipment.

Frequently Asked Questions (FAQs)

Can I use baking soda to raise the alkalinity in the reef tank?

Using baking soda is one of the safest ways to raise alkalinity in the water of the reef tank. However, you can either use soda ash or baking soda depending on the level of pH in the water.

When your reef tank has a higher level of pH, it is better to use the baking soda to raise the alkalinity level in the water. It is because sodium bicarbonate can lower the pH level a bit.

You might prefer using soda ash when the pH level is comparatively low. If you use soda ash with a reef tank that comes with a high pH level, the pH level will likely exacerbate.

What is the right level of alkalinity in the reef tank?

The right level of alkalinity in the reef tank varies from tank to tank and level of pH and calcium. Typically, the level of alkalinity in a reef tank should be within 8 to 12 dKH or 142 to 215 ppm when everything else is normal.

How can I lower the alkalinity in the reef tank?

Well, when the alkalinity level is too high than is required, you can go for lowering the alkalinity level in the reef tank. There are several ways to lower the alkalinity level in the reef tank. One of the common ways is to add CO2 or carbon dioxide by the gas exchange through aeration that takes place in the waterline. You can point the powerheads or return outlets at the waterline so that agitation is created. This method will help to lower the alkalinity level significantly.

The second way to lower the alkalinity level in the reef tank is quite a drastic one. You can apply vinegar or any organic acid in the reef tank to lower the alkalinity. When it comes to vinegar, you can use them directly to the tank. However, note that you need to be cautious enough to apply vinegar in a small quantity. If you do otherwise, you might experience large swings in alkalinity within a short time which is not good for the animals in the tank.

No matter which way you try, make sure that you are testing the pH and alkalinity regularly in the water of the reef tank. Though the testing frequency might vary, test the water at least once a week.

Baking powder or baking soda – which is better to raise alkalinity?

Do not confuse baking powder with baking soda. These two are different things. Baking powder is not as same as baking soda. Baking soda is made up of sodium bicarbonate and sodium while baking powder is the combination of sodium bicarbonate and potassium.

While baking soda is fine to be used in the reef tank to raise alkalinity, baking powder is not anything good to replace baking soda for raising alkalinity. So, make sure that you use baking soda in the reef tank water and keep the reef tank away from baking powder.

However, one good thing is that you can also use soda ash instead of baking soda in the reef tank raising alkalinity. It is really easy to make soda ash out of baking soda by using your oven.

How can I make soda ash from baking soda to use as an alkalinity booster?

Turning baking soda into soda ash is easier than you might think it to be. What you need is an oven and some baking soda or sodium bicarbonate. Here’s how you can turn the baking soda into soda ash to use the supplement for raising alkalinity:

  1. Preheat your oven to 300 degrees.
  2. Take a cookie sheet and spread some baking soda thinly over the sheet.
  3. Bake the baking soda for about 1 hour without interruption.
  4. Get the baking soda out from the oven. Mix the baked baking soda with some distilled water or RO/DI. And that’s your soda ash.

Final Thoughts

How much alkalinity level you should raise in the reef tank depends on the various factors such as calcium level, potassium level, pH level, etc. If you raise the alkalinity level too much or reduce the level too low, that’s not anything near a healthy practice.

Make sure that you know the right amount of alkalinity level in the reef tank water compared to the pH level, calcium level, and other factors. Increase the alkalinity level slowly and wisely.

We hope that you have now got a complete idea of how to raise alkalinity in the reef tank safely without harming the inhabitants and equipment of the tank.


  1. Wow how irresponsible can you be!!!!!!!!!!! It’s 1 TEASPOON not 1 TABLESPOON you absolute amateurs. NOBODY FOLLOW THIS ADVICE THEY ARE COSTING PEOPLE THOUSANDS OF DOLLARS!

    1. I sincerely apologize for the mistake. You are absolutely right and I have corrected it already. Thanks a lot Ben.

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