Water Chemistry (The Big 3)

Tier 3 of Water Parameters includes the major elements: alkalinity, calcium, and magnesium. These are referred to as the “Big 3” since stony corals in a reef aquarium need these elements to grow.  In a closed environment, these elements must be replenished regularly, as they are used to build the stony skeletal structures (the bones) of the coral.

The purpose of this short article is to summarize the current recommendations to maintain these parameters. As  I always say, never dose anything unless you test on a regular basis. Many smaller adjustments are better than a large change.

• Alkalinity/Calcium/Magnesium

  • Definition: These 3 parameters provide the necessary components for corals to build their calcium carbonate skeletons. Maintaining the proper ratio allows calcification to occur.
  • Measurement Options: Manual Titration Test Kit, Handheld Colorimeter, Automated Tester (Keep in mind all automated testers require regular maintenance to function correctly)
  • Nominal Range = 8-12 dkH
  • Remediation:
    • Low consumption – Use Kalkwasser (calcium hydroxide) for both equal amounts of Alkalinity and Calcium + a separate Magnesium supplement
    • Medium Consumption – Supplementation of commercial 3 Part solution or DIY solutions based on food or lab grade Sodium Carbonate/Bicarbonate, Calcium Chloride, Magnesium Chloride
    • Heavy Consumption – Calcium Reactor supplementation with proper ratio (typically 9:1) of calcium carbonate and magnesium media in the chamber.

Summary and Reading for Deeper Understanding

For more a comprehensive reading on this topic, I highly recommend ” A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH” and the 2002 article “Chemistry and the Aquarium: Solving Calcium and Alkalinity Problems” by Randy Holmes-Farley, a professional chemist and long time hobbyist.  He will explain how the three elements are related and how to achieve the correct balance.

Chemistry and the Aquarium: Solving Calcium and Alkalinity Problems” by Randy Holmes-Farley

The Reef Chemistry calculator by J.Dieck  is also a great tool for measuring and calculating alkalinity, calcium, and magnesium products. Based on the tank volume, the product used, the current measurements, and the target nominal, it will calculate and tell you what needs to be dosed.

I understand most people are hoping for quick videos and articles, but publications like these are still invaluable, to create a platform to provide deeper understanding.  There is no simple solutions when it comes to recreating nature. This is the challenge that has kept me in this hobby for over 35 years, and I have learned from experience how to succeed. It is more defined today than when I first started, for sure.

The advancements in ICP water testing have opened up new questions about how these elements impact biological health.  It’s similar to how we humans take supplements when we do not consume a well balanced diet. All the livestock in our aquariums are at our mercy to provide them everything they need to thrive. That is the goal we are trying to achieve.

The next logical progression (step) is to dive into the world of other macro and micro trace elements.

Till then, happy reefing.