Looking at a fish tank can be mesmerising. You can actually see how fishes react to its captive surrounding, and watch aquatics plants and algae grow naturally.

Although the plants and driftwoods in a planted freshwater fish tank looks great, algae don’t stand out. They make your tank look green and dirty. But on the other hand, if you look at a reef tank (saltwater tank) algae’s make it look beautiful, especially the Coralline Algae.

What is Coralline Algae?

Have you ever seen those rock-hard substances in the sea while scuba diving or snorkeling? Those are Coralline algae. These are the architects of the coral reef. Unlike regular algae, this algae have vibrant colors such as pink, purple or other shades of red.

They have two different kinds of forms: Geniculate and Non-Geniculate.

  • Geniculate: They are also known as articulate corallines. It includes branching, tree-like organisms that are quite flexible and has non-calcified sections.
  • Non-Geniculate: You may also call them as non-articulated corallines. It is the common encrusting and planting reef tank variety. It develops over time, usually seen on coral skeletons, live rock, shells, plastics, glass and other algae.
    Matured pink coralline algae can produce knobby jutting that provides micro-habitats for invertebrates. Some others are known to produce chemicals that promote the settlement of the larvae of certain insects.
    Lesser known facts include that chitons, urchins and limpets would not have existed if it were not for conservation by coralline algae formations.

Coral Reef and Coralline Algae

Coral reefs are a marine ecosystem. A reef is formed by colonies of coral polyps, which are held together by calcium carbonate. Lots of science behind this simple rock.

Coral reefs help maintain the ecosystem as well as promotes tourism and protects the shoreline. They are very fragile due to water conditions and can easily be damaged. Even us human being can damage the corals just by merely using sunscreen before a snorkeling session.

Oh, these corals can be really sharp, and anyone can easily be hurt by just stepping on it. So next time when you see a coral, be very careful.

The coralline algae are the unsung architect of the coral reef. It is mainly responsible for holding the coral into place. They grow over the crust of the coral reefs protecting the reef from any kind of unwanted danger. Just like the cement which holds the bricks in the wall.

The algae are a very slow grower. It grows from 0.4 inches – 1.2 inches annually. These kinds of algae come in different shapes, size, color and texture.

Coralline Algae

The Role of Coralline Algae in Your Aquarium (Reef Tank)

Fishes live in the rivers, oceans and seas. But they also live in glass cubical tanks. But what makes the glass tank into an aquarium?

Proper filtration, the right amount of pH in the water, substrate, aquatic plants, stones, driftwoods, coralline algae etc. But can you put coralline algae and aquatic plants together? No, you cannot. Both plants and coralline algae have got different needs in order to grow.

Coralline algae are grown in reef tanks, or we know them as saltwater tanks. Hobbyists usually cultivate coralline algae in their tank.  The role of coralline algae in a reef tank is almost the same as in the coral reef. It stabilises the rocks and coral reef in your tank, prevents unwanted algae and maintains the ecosystem in the tank.

How to Grow Coralline Algae in Salt Water Aquarium?

You might think that growing coralline algae is a hard job. Apparently, it is not. In order to grow coralline algae, the algae must be brought physically into the tank in order to improve and reproduce.

The algae can be brought into the tank by introducing a live coralline covered rock, coralline scraping from another tank or by commercial coralline starter pack.

Adding the algae is just the starting. To grow it properly a lot of other things needs to be done, such as proper filtration, water parameters, lighting, grooming etc. The most important things needed to grow the algae is adequate lighting and water parameters.

All hobbyists know that the more light there is, the more algae you get. But in this case, the lighting is still debatable. Different type of coralline algae needs a different kind of light. Some needs more and some requires less.

The water parameters are almost the same for all spices of coralline algae. The carbonate alkalinity needs to be between 2.5 and 4.0 meq/L (7-12 dKH) whereas phosphates and nitrates need to be low. If all the factors required to grow coralline algae can be maintained, the algae will flourish. And with the help of powerhead, the existing algae will spread throughout the tank and grow.

Coralline Algae Lighting Requirements

Healthy growth of coralline algae can be radicle to lighting. Although lighting preferences may vary on the type of algae and the tank environment, you still need to keep a few rules in mind when you establish a coralline colony:

  • Optimal lighting: There’s nothing called a lighting solution that could possibly be the best for every coralline alga. Every alga is unique and has its own preferences. It is noteworthy that most of the majority of coralline algae develops best if 10,000K and Actinic Blue lights can be used at an intensity of 1.6 watts per tank gallon. Our suggestion would be to adjust the lighting to satisfy the coralline consistently. Be patient!
  • Natural Light Cycles: Make the best use of light cycles that imitate sunlight duration. Know that coralline algae are photosensitive; too much exposure to the light may result in light shock that turns the damaged portions into white. But that does not necessarily mean that all the white spots are due to light trauma.

Coralline Algae Water Chemistry

Marine lives, along with coralline algae thrive once water parameters get into a permanent state. You can do this by regularly testing the water with pH test kits and changing the water more frequently. Since it’s not a good idea to shock your aquarium with a large number of water changes, you can take other measures.

As a general rule, try to follow a dynamic water chemistry parameter:

  • Calcium: 350 – 480 ppm
  • Alkalinity: 2.8 – 4.3meq/L or 7 – 12 DKH
  • pH: 7.9 – 8.3
  • Magnesium: 1300 – 1380 ppm
  • Phosphates: no more than 0.25 ppm
  • Nitrates: no more than 5 ppm
  • Temperature: 78 – 80-degree Fahrenheit

Causes of Disappearing Coralline Algae

The disappearance of coralline algae could be attributed for many reasons.

The first thing that comes into your mind when you think of coralline algae is that it’s the stuff that takes over the tanks! Well, it’s not too surprising, but know that it’s one of the most attractive species that’s useful in dissolving organic wastes in the tank and is an inherent part of the food for a wide range of little critters.

This part of algae is actually very desirable and proves to be essential for the tank environment.

While all of them are not good, many hold different functions enclosed in a tank environment as they do in a vast ocean. We would appreciate algae as a fantastic indicator of how well the mini ocean is performing.

You need to be wary of the magnesium, calcium, alkalinity and most importantly the water in the tank system. If there’s anything less or over in the tank parameters, it’s going to cause an undesirable environment within the tank system, affecting the coralline algae.

The strontium levels in the tank system are essential. You must have traces of it. Oceanic salt does not contain Strontium, and therefore, you will see a huge difference in certain brands that have Strontium as an ingredient in their salt.

The most effective way of presenting coralline algae into the tank system is through the inception of premium live rock, which does have a good number of coralline algae. The algae would typically appear to be a dark purple, pink, red, green and some similar shades.

Remember, if you can keep the tank environment stable, then you are more likely to prevent coralline algae from disappearing.

Additional Read: How To Increase Calcium In a Reef Aquarium


Coralline Algae can grow in the dimmest area and also the lightest area. Maintaining and improving it is not that hard. Moving it from here to there can kill it quickly.

The fish tanks need to be cleaned once every week. Properly not cleaning can also be the cause of killing it. Not having the right amount of water chemistry will even kill it.

Without proper maintenance, the colourful looking algae will turn white and eventually die. The reason for coralline algae in the coral reef to die is another different story. And humans contribute the most in killing it.

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