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4 Best Macroalgae for a Refugium (With Pictures)

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By Lindsey Stanton

Besides the other obvious stuff like air pumps, filters, and water pumps, a refugium is also a great addition to any aquarium, especially saltwater aquariums.

A refugium is a like a separate little tank where you can grow beneficial bacteria, algae, and let little microscopic critters flourish, all things which can be very beneficial to the health of your fish tank. But what is the best macroalgae for a refugium, you ask? This article covers all you need to know and more.

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What Is Macroalgae?

Macroalgae is a member of the aquatic plant group known as algae. These are quite primitive photosynthetic plants, and macroalgae is a multi-cell organism that consists of hundreds or even thousands of individual cells. Do not confuse macroalgae with sea plants and seaweed, both of which are more closely related to land plants, whereas macroalgae is purely a water plant.

Macroalgae actually absorbs all of the nutrients it needs to survive from the surrounding waters which it lives in, kind of like how a sponge soaks up water. Most types of macroalgae will fall into four specific groups: blue-green algae, green algae, brown algae, and red algae.

Macroalgae is almost always found in reefs and hard sea beds, as well as on rocks, boats, and other hard surfaces. They like to attach themselves to hard surfaces which are surrounded by nutrient-rich waters.

What Is the Best Macroalgae for a Refugium & Why?

amphipods chaetomorpha macroalgae

In our opinion, the best type of macroalgae to have in your refugium is Chaeto (you can buy it here at Amazon). One of the most important things that Chaeto does for your aquarium, specifically in saltwater reefs, is to absorb excess amounts of phosphates and nitrates.

This is important because both nitrates and phosphates can be harmful or even deadly to the inhabitants of your fish tank. Another reason why we feel Chaeto is the best option for your refugium is that it makes for an amazing home for copepods.

Copepods are little microscopic creatures present in the water, and when given a chance to thrive, these things can make for a pretty good food source for smaller fish and for coral, thus reducing the need for you to feed them.

Copepods are often eaten way too fast by the residents of your aquarium, so having a sizeable population thriving in a Chaeto growth is a great way to maintain a healthy amount of them.

Without a doubt, one of the best parts of having Chaeto in your refugium is that it does not go sexual like other forms of macroalgae tend to do. This means that it will not die and release all of those absorbed nutrients back into the water, something that can kill your fish.

There is also the fact that this stuff will grow exponentially with some good lighting, so maintaining a healthy population of Chaeto is fairly easy.

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Different Types of Macroalgae

There are a few main types of macroalgae that you can use for the refugium in your aquarium, each of which looks a little different, does different things, and has different characteristics.

There are four main types of macroalgae that are common in aquariums and refugiums, so let’s talk about those really quick.

1. Chaetomorpha

Image Credit: Pavaphon Supanantananont, Shutterstock

This type of macroalgae is more commonly known as Chaeto, and it is one of the top choices for reef enthusiasts around the world. This stuff looks like spaghetti and it grows very fast. It grows in a ball of spaghetti like strings and it will expand pretty quickly given the right circumstances. One of the biggest benefits of having this type of Macroalgae in the water is that it does not go sexual.

When macroalgae goes sexual, it means that it releases spores into the water to reproduce, while at the same time, the Chaeto that has been thriving will all die, and this means that it releases everything that it has absorbed back into the water; something that is, of course, not very good and can be very dangerous to any of the creatures living in your aquarium.

Interestingly enough, Chaeto is one of the few types of macroalgae that floats around in the water, so you probably only want to have it in your refugium, but not in the aquarium itself because it can get caught on virtually anything and clog up pumps too. This stuff is actually fairly cheap, which is an obvious bonus for anyone.

2. Dragon’s Tongue

Dragon's Tongue Algae
Image Credit: chonlasub woravichan, Shutterstock

Yet another popular type of macroalgae, dragon’s tongue is a really popular choice for both aquariums and refugiums. This stuff is pretty fragile and kind of looks like pieces of gelatin. Dragon’s tongue has reddish-orange blades, kind of like smaller pieces of grass, except of course it is not green.

This stuff does look really nice and it also does a good job at exporting nutrients. The downside to it is that it grows fairly slowly, thus taking a while to get established, plus it is also fairly expensive.

3. Caulerpa

Caulerpa Prolifera live macroalgae

This is another fairly popular for people who like to have macroalgae in their aquariums or refugiums. This type of macroalgae can come in many forms, such as ferns, grapes, and flat blade types too.

Caulerpa macro algae mainly grow on rocks on other hard surfaces, it grows very quickly, and it also works as a fantastic place to house good inverts, with those being the bacteria and microorganisms that help filter out your water and keep it clean.

This stuff does grow very fast and if not kept in check it can overtake other types of algae very fast. Moreover, a big downside to this stuff is that it will go sexual, thus releasing spores into the water.

Caulerpa is not all that expensive and it does have beneficial aspects. However, the fact that it does grow so fast that it can take over other types of algae, as well the fact that it goes sexual, are two downsides to Caulerpa.

4. Money Plant

Aquatic Arts Moneywort plant

A really interesting part about this type of algae is that it is calcerous in nature, which means that it feeds on the calcium present in the water. It will absorb calcium in the water, but when it dies, it will release it back into the water. This type of algae is not fantastic for nutrient export because it does grow fairly slowly, but it does still have beneficial properties.

The money plant is an encrusting type of algae, which means that it will slowly expand both vertically and horizontally across hard surfaces. The good part about its slow growth is that it is relatively easy to keep in check and will not negatively affect the growth of other types of algae in the water.

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Why Do You Need Macroalgae for a Refugium?

There are a few different reasons why having macroalgae in your refugium is very beneficial for the health of your fish tank. First of all, macroalgae will help pull unused nutrients out of the water. Nutrients such as ammonia, nitrite, nitrate, and phosphate are all things that can harm or kill your fish.

Macroalgae will absorb those things and keep them away from your fish. In essence, a refugium with macroalgae can serve as a great secondary filter to help keep your fish tank water clean and free of unwanted organic compounds. Moreover, it will also absorb the nutrients that other forms of undesirable algae use to grow, thus helping you control unwanted algae blooms with ease.

A refugium with macroalgae is also great for allowing the reproduction of small creatures and microorganisms that would otherwise not get a chance to survive in a really busy tank because they would most likely all get eaten before a sizable population can develop. These organisms that grow in the refugium can then serve as a pretty decent food source for the fish and coral in your aquarium, plus they do a pretty good job at cleaning up waste and uneaten food.

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The fact of the matter is that any saltwater aquarium is going to be much better off if you have a refugium with macroalgae growing in it. This stuff will help keep the water clean, and it will help the growth of microorganism populations too. Just keep our macroalgae recommendations in mind and you will have no trouble in being a successful aquarist.

Featured Image Credit: Caulerpa Prolifera live macroalgae

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