Magnesium is the silent partner of calcium and alkalinity. It plays one of the most critical roles in a reef tank. Without proper levels of magnesium, calcium and alkalinity will combine and precipitate (i.e. fall) out of solution. As a result, both essential elements become unusable to the corals in the aquarium. Therefore, it is vital that these elements are properly balanced.
If you haven’t already, check out our blogs on calcium and alkalinity:
What is Magnesium?
Magnesium is one of the most common chemical elements found on Earth. It is an essential component of many chemical processes on land, the ocean and inside the human body. In the human body, it is vital for helping maintain a healthy heartbeat, among many other functions. In seawater, it is the third most abundant element after sodium and chlorine.
Why is it Important?
Magnesium helps maintain calcium and alkalinity levels in a reef tank. If levels are too low, calcium will combine with alkalinity to create calcium carbonate in the water column. This creates a “snow” that can stick to pumps, impellers and heaters instead of being used by corals to build their skeletons. Hard corals also use magnesium to build their skeletons.
What is the Optimal Range?
Reef Aquariums: 1250-1350 ppm
Tools for Measuring Magnesium
Standard Test Kit:
Standard test kits are the most common tool used for measuring magnesium levels. They are readily available for purchase in most stores.
Generally, these test kits are inexpensive and fairly easy to use. However, they certainly do not come without flaw. Typically, standard test kits are not as accurate as other methods of testing and the results can often be inconsistent.
ICP-OES Water Analysis:
Take the guesswork out of the testing process by using a water analysis to detect magnesium and other elements through a professional lab. Simply buy the kit, collect the water sample, and mail it in. It’s that simple!
Most labs will complete results within about a week or so. The results then provide recommendations for corrective measures to improve water quality.
Learn More About ATI’s ICP Test Kit:
How to Maintain Magnesium Levels
A popular misconception is that testing magnesium levels regularly is not needed, and that water changes alone are sufficient enough for maintenance. For tanks with minimal or no hard corals, this can be true. However, hobbyists often discover that magnesium is too low only after calcium, alkalinity and pH levels have already become unstable.
For most aquariums, we advise testing magnesium levels at least once every two weeks. We also recommend testing immediately after finding either calcium and/or alkalinity levels are out of balance.
The Relationship Between Calcium, Alkalinity, and Magnesium + How to Prevent Calcium Carbonate from Precipitating out of the Water
As mentioned above, proper magnesium levels prevent calcium carbonate from precipitating out of the water. So how does it work it’s magic? Essentially, magnesium binds to the surface of calcium carbonate crystals. This effectively stops calcium carbonate crystal from growing and precipitating out of the aquarium water.
Without proper magnesium levels, keeping calcium and alkalinity stable is an overwhelming challenge. And without the correct alkalinity and calcium levels to go along with it, maintaining a successful reef is nearly impossible! Therefore, we highly recommend that testing is regularly conducted. By maintaining levels between 1250-1350 consistently, this will prevent potential issues, keeping your corals healthy and thriving!
Have a question? Feel free to contact us for more details regarding how to maintain your tank. If you are in the market for new tank equipment or supplies, please visit our website here: ATI North America.