How to Raise Alkalinity in Reef Tank {Top 5 Ways Explained}

Are you looking to raise alkalinity in your reef tank safely and effectively? What does low alkalinity do to your reef tank and surrounding marine life?

In this article, we’ll find out the methods used to raise alkalinity in a reef tank.

How to Raise Alkalinity in Reef Tank: Baking soda, soda ash, limewater, calcium carbonate and commercial alkaline boosters will help you gradually raise the dKH or alkalinity levels in your reef tank. 

How Should I Raise Alkalinity In My Reef Tank?

The marine life in your reef tank will suffer from health issues if the overall amount of alkalinity is too low.

You should raise your alkalinity in a reef tank using chemicals or commercial products that are premixed alkaline boosters. You can also use the following three ingredients:

  • Baking soda
  • Lime water
  • Soda ash

Why is Alkalinity Important?

The buffering capacity in your reef tank is controlled by alkalinity. In other words alkalinity controls the pH in your reef tank’s water.

Alkalinity prevents:

  • Coral bleaching
  • Spikes or loss of pH
  • Tissue loss

Alkalinity also allows your tank equipment to work at peak performance.

How Do You Measure Alkalinity?

We measure alkalinity by ppm or parts per million. You will commonly see the letters kH or carbonate hardness to signify the alkalinity levels when performing tank water tests.

The total alkalinity in a reef tank can be measured with the three letters dKH instead of ppm.

  • 1 dKH = 17.9 ppm

The optimal balance of alkalinity is around 8-12 dKH or 142-215 ppm in a reef tank.

Do I Need Alkalinity Tests?

Yes. The alkalinity test that you perform will help make sure the calcification of corals is taking place while maintaining its formation. If alkalinity is not regulated, you will notice stress from your marine life as well.

You can test alkalinity in your reef tank with two main ways:

  1. Test strips
  2. Test kits

1. Test Strips

Test strips are easy and cheap. The reason why many aquarists choose not to use test strips is because they are not as accurate as test kits.

You are aiming to dip a part of the test strip into the reef tank for a period of 10 seconds. Usually a color code identifies the alkalinity level on a test strip.

2. Test Kits

With the test kit, you should collect some of the water from the reef tank and place it in the test tube. You will then mix the solution in the test kit with the tank water.

After you mix them well, you will receive your results. The color scale provided with the test kits will help you identify the total level of alkalinity in your reef tank water.

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What Are Some Ways of Raising Alkalinity in a Reef Tank?

The organisms in your reef tank need a healthy range of alkalinity to thrive. Here are some ways that you can raise alkalinity in your reef tank:

  1. soda ash
  2. sodium bicarbonate (baking soda)
  3. limewater
  4. calcium carbonate (carbon dioxide reactors)
  5. alkalinity boosters and calcium supplements

1. Soda Ash

Soda ash is available in your local fish shop or you can purchase it online. The instructions included will help you to understand how to gradually raise your alkalinity levels.

If you use too much soda ash you can actually cause coral bleaching or tissue loss.

2. Sodium Bicarbonate (Baking Soda)

You can also use baking soda gradually to raise alkalinity in your reef tank water. Do not try to raise the alkalinity more than 1.4 dKH per day. A teaspoon of baking soda could raise the dKH level by 1 point.

3. Limewater

Limewater is used to help balance levels of calcium and alkalinity. What you are doing to raise or decrease calcium, you end up affecting the level of alkaline in your water as well.

4. Calcium carbonate (Carbon Dioxide Reactors)

Alternatively if you have access to calcium carbonate, or carbon dioxide reactors as you can help to increase the levels of alkalinity and calcium at the same time.

5. Alkalinity and Calcium Supplements

Alkalinity and calcium supplements are also available as commercial products. They come with instructions to help you understand how much you need to add in to help raise calcium and alkalinity levels simultaneously.

  1. The trick is to work slowly and gradually to maintain the balance of both calcium and alkalinity.
  2. Also keep in mind that if magnesium levels are low in your reef tank, the supplements or alkaline boosters that you are using may not work effectively.

Can I Use Baking Soda to Raise Alkalinity in the Reef Tank?

Baking soda is one of the most popular, cheapest and safest ways to raise alkalinity levels in your reef tank.

If your reef tank has a high pH reading then you can use baking soda to raise the alkalinity. If your pH level is low, alternatively you should use soda ash instead.

How Can I Lower the Alkalinity In a Reef Tank?

If you are looking to lower the alkalinity level in your reef tank, you can add CO2 through carbon dioxide cartridges or increase water agitation with powerheads.

Organic acid or vinegar also helps to lower alkalinity in a reef tank. Do so cautiously because you may end up with a large spike of alkalinity with a very small dose.


With any method listed in today’s article, we urge you to exercise caution and focus on working patiently and gradually. Alkalinity tests should be performed weekly or at least once every two weeks.

Your reef tank can raise its alkalinity levels with your help by adding baking soda, soda ash or simply opt for commercial alkaline boosters that are sold commercially.


Thank you for stopping by at We have plenty of articles on a wide variety of marine life that may also pique your interest. See you again soon!

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.