Alkalinity in a Reef Tank - Determining Alkalinity Consumption
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Alkalinity in a Reef Tank - Determining Alkalinity Consumption

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Last updated on November 17th, 2023


Alkalinity in a Reef Tank - Determining Alkalinity Consumption

Alkalinity in a Reef Tank - Determining Alkalinity Consumption

Alkalinity in a reef tank is one of the most important parameters behind Temperature and Salinity. Maintaining stable alkalinity in a reef tank is key to coral growth and success. In order to maintain stable alkalinity levels, you first need to determine alkalinity consumption in your tank. I will walk you through how to determine alkalinity usage in your reef tank.

Determining alkalinity usage in a reef tank is actually quite simple. The best part is that all of the tools you need are right here on Reef Stable.

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The best way to determine alkalinity usage in a reef tank requires turning off all dosing and alkalinity buffer methods. This means not adding kalkwasser, stopping your calcium reactors, and turning off dosing for 2 part.

WARNING: If you have a lot of SPS coral colonies, you may not be able to safely turn off these additives. If this is the case, the method of determining alkalinity consumption below will tell you how much more (or less) alkalinity you need to add to your reef tank daily.

Why Should I determine Alkalinity Usage?

The simple answer is to keep coral alive and growing. As coral grows, it pulls alkalinity (carbonate) and calcium from the water and grows the skeleton. If the alkalinity levels drop too low, then coral can either die, or at least, stop growing. To add these chemicals back to the reef tank, you need to know the reef tank's alkalinity usage.

How to Determine Alkalinity Usage in a Reef Tank

  1. Turn off all Buffers for Alkalinity in a Reef Tank. This includes 2 part, kalkwasser, and calcium reactors. If you can't do this because your coral needs the supply, thats okay. The rest of the steps will tell you how much more (or less) alkalinity you need to add to your reef tank.
  2. Measure the Alkalinity in the Reef Tank. I recommend using the Hanna Alkalinity Checker in order to get consistent readings.
  3. Track the current Alkalinity in the Reef Tank. This can be done with a pen and paper, marker board, or the Reef Stable Parameter Log. Regardless of which method you use, make sure to note the current time.
  4. Wait EXACTLY 24 hours. We want to see what the alkalinity consumption is in a a full day. Coral will consume alkalinity in a reef tank at different speeds based on the lighting, flow, and other reef tank conditions. If you're off by a few minutes, it won't change the outcome, but a couple hours will.
  5. Measure the Alkalinity in the Reef Tank again. For consistent readings, use the same test kit, in the same lighting as the first test. The Hanna Alkalinity Checker makes this simple as it doesn't rely on you determining color differences.
  6. Track the Alkalinity in the Reef Tank the same way as the step above.
  7. Determine the Alkalinity consumption in the reef tank. Do this by taking the first measurement and subtracting the second measurement.

    The Reef Stable Parameter Log Premium Subscription will handle this consumption calculation for you under the "Analysis" tab. This will also calculate calcium and magnesium usage in the same way.

    Measurement 1 - Measurement 2 = Alkalinity Used Per day.

Determine How Much Alkalinity Buffer to Add to a Reef Tank

  1. Now that you know how much alkalinity is used in the reef tank, you can figure out how much alkalinity buffer to add by using the Reef Stable Dosing Calculator.
  2. You can then adjust this up or down using the steps above to determine how much more or less alkalinity you need in your reef tank.

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Alkalinity in a Reef Tank is among the most important parameters to dial in for coral growth and health. Alkalinity usage in a Reef Tank is even more important when keeping more difficult corals such as LPS and SPS coral. This method of determining alkalinity usage in a reef tank and how much of a product to add is one of the most important secrets to unlocking a beautiful reef tank.

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About the Author

Reef Stable Founder John Krenzer

John is a Software Engineer with a passion for saltwater aquariums, as well as the founder and president of Reef Stable. He started in the aquarium hobby as a child with a 20 gallon freshwater aquarium. His interest in aquarium life grew and in 2008, John set up his first saltwater aquarium.

Today, John maintains an over 300 gallon reef tank system, consisting of a 120g reef and a 210g reef. These large tanks are contained within the same system, sharing a sump as a means to reduce total maintenance and increase total water volume.

John writes articles for the blog as a means to learn about more reef aquarium topics. These articles act as a reference for the readers as well as himself. John updates these articles frequently to provide additional information or make corrections as new information becomes available.

If you would like to request an article, tank tour article, or to collaborate, let me know via the Contact Me Page!

About Reef Stable

Reef Stable was initially founded in 2019 as a reef tank parameter log to fill a need. Reef Stable quickly grew, becoming a location to solve all of your reef tank problems as well as a place to learn.

Reef Stable now provides a Reef Blog, Reef Aquarium Guides, Coral Care Guides, Identification and Solutions for Pests and Algae, and Reef Dosing Calculators, in addition to the original Reef Parameter Log.

Reef Stable continues to grow, striving to provide a single location for all your reef tank needs!

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