Success in a Reef: Introduction to the Foundation Elements

Success in a Reef: Introduction to the Foundation Elements.

          When you think about the foundation of a reef, you’re probably thinking about rocks, and by now, corals as well. Pat yourself on the back, because you’re right. In fact, well developed reefs are covered from head to toe in coral. We consider it a true marvel of the world that these creatures, through thousands of years, have been able to create incredible monuments, like the Great Barrier Reef. What I am referring to, however, is what these organisms utilize to build these reefs; the super saturated, highly abundant elements they pull from the water. These foundation elements, which are primarily Calcium(Ca), Magnesium(Mg), and Alkalinity compounds, are the building blocks of a Coral Reef. Literally. Each and every creature in the sea utilize or rely on these foundation elements, in one way or another. Maintaining these elements is a continuous (albeit painless) battle, with ups and downs, and is absolutely crucial to our success as reef aquarists, but luckily, companies such as Red Sea and Salifert make this very simple with their pharmaceutical grade, well concentrated products and highly accurate, easy to use tests. Together, we’ll explore these foundation elements, and touch briefly on the importance of maintaining their stability within our aquariums.

The Foundation Elements

Calcium (Ca)

Let’s begin with the easy one. Wait... Easy? Here is what I mean: Calcium, like the rest of your tank parameters, can fluctuate and needs to be stable in order for things to operate smoothly, however, unlike some other parameters, a fluctuating calcium level is not very dangerous in the majority of cases. As long as Calcium is kept within the proper range (350-500), the vast majority of reef livestock will not notice temporary fluctuations. Problems arise with Calcium when it is kept too low or is fluctuating for long periods of time. Calcium is also very easy to raise, should it fall, using [Red Sea Reef Foundation A, Seachem Reef Fusion 1, or aquavitro Calcification*], and easy to correct, should it become oversaturated (too high), via water changes. Rest assured, though, using high quality additives, such as the aforementioned, the “chemistry” of everything will be taken care of, and Blue Fish Aquarium will be here to help you, from figuring out how to apply it to your aquarium, to making sense of the changes these additives will have on your aquarium. We are here to help, every step of the way, because it’s never been easier to have a thriving, successful coral reef within your home.

Magnesium (Mg)

Magnesium is my favorite, because it can behave as, and is known for being, a passive foundation element. While still critically important, Magnesium, like the rest of your tank parameters, is susceptible to fluctuations, which means it needs to be stable in order for things to operate smoothly, however, unlike some other parameters, Magnesium has a very wide range of acceptable levels. As long as Magnesium is kept within the proper range (1100-1500), the vast majority of reef livestock will not notice any fluctuations. Problems arise with Magnesium when it is kept too low or is fluctuating widely (by several hundred ppm per day) for long periods of time. Magnesium is also very easy to increase, should it fall, using [Red Sea Foundation C or aquavitro Ions*], and easy to correct, should it become oversaturated (too high), via water changes. Under normal operation, standard two-part dosing, as well as water changes, will keep this parameter in check. The tricky part with Magnesium is the rate at which it is consumed. Every aquarium is different, and will utilize magnesium at different rates, and so, some aquarists will find a deficit and need to correct it, however, most aquariums will never need to adjust this parameter and so the passive foundation element is also the easiest to control. Magnesium also plays a very critical role in seawater, and especially our aquariums: it allows calcium and alkalinity to remain stable at their saturation levels, which is absolutely critical in home aquaria, because it allows us to maintain heightened parameters which are well above typical seawater saturation levels. These heightened parameters carry an array of benefits when it comes to coral growing. For this reason, we love and appreciate the effectual Magnesium.


This is the one to watch, as far as foundation elements go, because this one has a habit of being “fine until it isn’t”, because when the alkalinity of a system fluctuates rapidly, the entire tank notices. Alkalinity, as a parameter, is comprised of multiple seawater components, such as Calcium, Carbonates, Phosphates, and more. Testing equipment will utilize these, perform some math, and come up with our focal parameter. For ease of use, we prefer reading our Alkalinity measurements in dKH (the hobby standard), or less commonly, PPM. Alkalinity, at its basic core, is a measure of your aquariums ability to buffer acids, and control pH, or rather, the mechanism with which your tank maintains critical acid buffer regulation, and balance. A low alkalinity comes with a host of problems, namely, the inability to stabilize pH and to resist dangerous fluctuations in the acidity of your aquarium water. A High alkalinity can cause the rest of your parameters to precipitate out, similarly causing a whole host of possible issues. Generally speaking, a swing in either direction of .4-.6 dKH or less is considered tolerable, but this is very subjective as sensitive reef specimen, such as Acropora and Euphyllia (now known as Fimbriaphyllia1) are more likely to respond negatively to any alkalinity fluctuation, and quickly. This means that, regrettably, some corals are less forgiving of swings in Alkalinity parameters. Worry not, however, as companies like Red Sea and Salifert make very easy to use and accurate testing equipment, such as [Reef Foundation Test Kit], that is affordable and can be used right at home. This will allow you to monitor your alkalinity on a regular basis, and make changes as necessary. Much like Calcium and Magnesium, Alkalinity is simple to control, so long as you are using high quality additives, and a salt mix that does not exceed your target parameter(s).

Test kits? Chemistry?

Regrettably, an ecosystem as complex as the ocean requires a bit of scientific know-how, if you want to be successful. However, this doesn’t mean hours of study, quizzes, or homework – quite the opposite, in fact, you’ll find years of enjoyment and pick up some marketable skills along the way. Maintaining these parameters is generally simple because the hard science behind it is already done for you, when using high quality additives and test kits. The challenging part is making sense of the numbers, because fluctuations can be a result of any number of things. Conditions such as a large coral purchase and addition to the aquarium, a power outage, or even the alteration of equipment, can cause systems of all sizes to change unexpectedly, further emphasizing the need to be prepared. These days, thankfully, its never been easier to prevent.

OK, I’m on board, but where do I begin?

Right here, at Blue Fish Aquarium. We offer a lot of free services (for local, walk-in customers only) which will aid you in the success of your aquarium. We will test your aquarium water to get an idea of how things look, and the conditions they’re living in, at no/little cost to you. We will then attempt to evaluate (and talk about how to change) why these fluctuations occurred. However, sometimes a single water test will only tell us part of the equation, and unfortunately, can be a bit misleading. For this reason, we do recommend keeping a record of your at-home test results. In the event we do not have enough information to diagnose a problem from one water sample, a historical record of your foundation element parameters will help us diagnose the situation with much greater accuracy, and much less loss. We will also provide you a written snapshot of your free water test each and every time, for your records and convenience.

Finally, rest assured, we are here to help you with your aquarium chemistry and tank parameters, every step of the way, to ensure your success. Our staff is expertly trained at recognizing the signs of an imbalance before it gets out of hand, as well as correcting them. We will walk you through every step of every test, as many times as you need, and also help you develop a dosing regimen that fits the unique demands of your system, to ensure the success of your reef for many generations to come.

 Author: Sean L

1 -  Luzon, Katrina S., et al. “Resurrecting a Subgenus to Genus: Molecular Phylogeny of Euphyllia and Fimbriaphyllia (Order Scleractinia; Family Euphyllidae; Clade V).” PeerJ, vol. 5, Dec. 2017, p. e4074. PubMed Central,


* aquavitro - we sell aquavitro products but no company is authorized to advertise pricing or sell online






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