Saltwater Algae Control: Red Algae

After posting our guide on saltwater algae control, some of our readers have asked about the different types of saltwater algae. Most were surprised that there are actual benefits to having algae in their aquaria! Judging by the responses, it’s clear that they don’t get much love from you fellow aquarists. So, I’ve taken it upon myself to spread the love for this misunderstood aquarium “plant” and will be writing a series to expand on my previous post on algae control.

What Is Red Algae?

Red algae or Rhodophyta as it is scientifically known is a type of algae that is primarily seen in saltwater aquariums, but is found in freshwater aquariums as well, though limited to a very few species.

The red algae gets its color from the pigment phycoerythin which gives the algae the color by absorbing blue light and reflecting red light.

Probably not the worst algae to come and squat in your aquarium, red algae can be a bit beneficial while it’s there. This might come as a surprise to you but red algae need not necessarily be red in color.

Although it is mainly seen in the color red, it is often seen in black or even blue and green at times. Unlike many other forms of algae, red algae is multi-cellular in nature and are widely misunderstood by many hobbyists.

Often misunderstood, hobbyists are often unaware of the benefits of this algae. Though, if the algae growth is not regulated it can become quite a problem. If you can keep the red algae under control then it’s beneficial to your tank and it improves the overall health of your aquarium’s ecosystem through some of its many benefits.

Rhodophyta, phylum (division) of the kingdom Protista consisting of the photosynthetic organisms commonly known as red algae. Red algae, by far is the most common seaweed found in the world’s oceans.

Unique to the red algae and the cyanobacteria, members of this division have a clear red or purplish color supplied by pigments called phycobilins. The chloroplasts (cells that produce food from sunlight) of red algae are believed to be derived from cyanobacteria that formed an ancient symbiotic relationship with the algae.

Hobbyists have a preconceived notion that all algae are bad algae, but if we take a closer look at how saltwater ecosystems work in real life we’ll see that algae plays a very important role in the sustenance of the ecosystem.

Take a little scuba dive or go snorkeling into the Australian great barrier reef and you’ll see that the algae is a natural part of this ecosystem and actually is beneficial to the reefs.

Advantages Of Red Algae

Like I previously mentioned, unlike many other algae, red algae is actually beneficial to your saltwater aquarium when it’s growth is controlled and managed well.

Experienced hobbyists often pay large amounts of money in order to get hold of some really good red algae because of the good it does by having them in the aquarium. Let’s take a look at some of the advantages that red algae has below:

1. Decreases The Chances Of Growth Of Unwanted Algae

With the presence of red algae in your aquarium, the chances of the growth of other algae in the aquarium are significantly reduced because the red algae fights for the same nutrients as the other algae do making it hard for both of them to survive.

If you have the presence of red algae in reasonable quantities across your aquarium from an early stage it will limit the chances of the outbreak of other unwanted algae that can ruin the health and cleanliness of your aquarium by absorbing the nutrients quickly.

2. Food For Fish

Certain types of fish often take quite a liking to the red algae. It not only absorbs the excess nutrients from the water, but also serves as a great source of food for your fish.

Check the type fo fish you have before ascertaining whether the presence of red algae is beneficial to your fish in terms of being a source of food. Since it is consumed by fish, its growth can often be regulated by adding red algae-eating fish into your tank.

3. Growth Of Coral Reefs

Red algae are found to be beneficial in the formation and sustenance of coral reefs naturally and in aquariums. Coralline red algae are one of the types of red algae that helps build coral reefs.

Some of the biggest natural coral reefs found around the world such as the Great Barrier Reef in Australia is supported by the growth of red algae in the reef.

4. Control Excess Nutrient Buildup

Red algae do a great job in controlling excessive nutrient buildup in the aquariums by absorbing them quickly for their own consumption and growth. This helps keep certain elements, especially nitrates and phosphates in check, thereby maintaining the right balance of these elements in the water as well a clean and healthy environment for your marine life.

Rhodophyta (red algae) have been found at depths of up to 879 ft (268 m), where the wavelength of light available for photosynthesis is very different from that in shallow water. However, a vast majority of the red algae used (as fish food) in the aquarium trade is found in

shallow waters inside the reef

Disadvantages Of Red Algae

Keeping the algae under control has a bunch of benefits, but if the growth is not controlled and the algae spread out of control, it can be quite a problem and it can cause a nuisance to a hobbyist. Red algae are one of the toughest algae to get rid of.

Removing them manually is the hardest among all the algae and it can be quite cumbersome to do so. Let us take a look at what are some of the disadvantages you could face if the red algae in your aquarium grows out of control:

1. Restricts The Growth Of Plants

Algae are known to be “shrewd” in nature, if you will, as they’re known to grow without much of a fuss with minimalistic needs.

Once they enter the aquarium and grow over and above what would be good for the aquarium it can cause problems to the other plants in the aquarium by absorbing all the nutrients very quickly leaving nothing for the plants to absorb. This will starve the plants from having access to basic nutrition that is required for their growth.

2. Unsightly Looks

Algae in general don’t really require an invitation to grow in particular areas of the aquarium, they tend to grow everywhere without notice which can be quite a problem for a hobbyist that’s looking for a “pretty” looking aquarium.

Red algae especially grow on live rocks and even plant leaves which can make them look quite unsightly in the aquarium.

3. Hard To Get Rid Of

Red algae is probably the hardest of the algae to get rid of. Scrubbing them off plant leaves or rocks is quite a task and it hardly gets the job done.

As a hobbyist, you’ve to be very careful in ensuring that you don’t have a red algae outbreak or you’ll find it quite hard to get rid of it.

Causes For Growth Of Red Algae

1. Contaminated Plants Or Fish

Plants or fish that have been bought from your local pet store can be the cause of the introduction of red algae in your aquarium. How, you ask? If red algae is found prominently in your area, especially in the pet store where you bought the plant and fish from, chances are that traces of red algae can be found on them.

They don’t necessarily have to be visible since algae are small multi-cellular organisms and when in small numbers can’t be seen by the naked eye. Once they enter your aquarium, even in those small numbers, you don’t need any introduction to their ability to quickly adapt and grow quickly.

2. Soil Used

The soil that lays beneath the substrate in your aquarium can also be a cause for the growth of red algae in your saltwater aquarium as they often have nutrients that aid the growth of red algae.

3. Low Light Levels

Red algae unlike traditional plants thrive in low lighting conditions which makes it so easy for them to survive in harsh conditions. They are often found up to depths of 879 feet under water where the amount of light available is very low and also at a completely different wavelength than what’s available at shallow surfaces.

How To Identify Red Algae

Red algae is characterized by its unique red-ish color that it gets from the pigment phycoerythin. Many people relate to algae with the color green but rhodophyta’s pigment absorbs blue light and reflects red light which gives the algae its unique color.

Feather/Leafy like structure of the Red Algae

It is a multi-cellular organism that grows in a leafy or feathery structure. They are often found growing on leaves of the plants in your aquarium and live rock.

Ways To Control Red Algae

1. Pre-Treatment Of Plants

Pre-treating your plants with bleach so that no red algae enter with it is a great way to make sure that you don’t allow red algae to enter through plants that might contain traces of it. 1:19 bleach to water ratio works really well for this procedure as it ensures that the bleach isn’t too concentrated and does not kill your plants but is just enough to get rid of any red algae if present.

During this process, the plants might lose some of their leaves but that shouldn’t worry you too much as with the ideal environment they’ll grow back before you know it.

2. Algae Eating Fish

Certain fish absolutely love to feast on red algae. Take a look at the current setup you have and then head out to your local pet/fish store and ask them for a red algae-eating fish that will go well with your current setup.

These fish will do a good job of limiting the growth of red algae which means you’ll be able to enjoy the benefits of red algae without having to get rid of them completely.

3. Controlled Photoperiod

Having too little light can be a cause of growth of the red algae as we previously saw. Too much light for extended periods in the aquarium can also mean that other unwanted algae can start growing.

So, it is important to balance the light that the aquarium gets to make certain that your plants get enough light but still control the growth of algae by not allowing too much or too little light.

4. Introduce A Lot Of Plants

Introducing a lot of plants into the aquarium is a good idea as all the nutrients that come from various sources will be absorbed by them and not be “orphaned”.

Such “orphaned” nutrients can lead to the growth of algae and help the algae spread at a very rapid pace as well. By introducing many plants into your aquarium you’ll starve any algae that’s present and also not allow any new algae to grow.

5. Copper Cleansing

Using copper to cleanse the aquarium and get rid of algae is another option, but should only be used as a last resort. This is because while the copper will completely kill the red algae, it might also kill some of the other marine plants of yours in the aquarium. So you should exercise this method with caution.

Though, the harmful effect is only limited to a couple of aquatic plants and most of the desirable aquatic plants aren’t harmed at all. As a matter of fact, many plants benefit from the copper that’s introduced while the algae gives way. Copper can be introduced into the aquarium in the form of copper sulfate among other options.

Get hold of a copper test kit in order to keep track of copper levels. While carrying out the procedure make sure that the fish are removed and kept separately and reintroduced into the tank only when the copper level is below detectable limits again.

These are a few really effective ways to control red algae although as a hobbyist you wouldn’t want to get rid of them completely because of their benefits. Try and keep the red algae quantities in check, but don’t remove them completely if you’d like to see the benefits of the red algae in your saltwater aquarium’s ecosystem.

Your Thoughts on Red Algae?

After reading this article I’m sure many hobbyists who previously had a misconception about algae being villains can now see their protagonistic side as well. Red algae can be a wonderful addition to your aquarium’s ecosystem helping it become more complete and natural.

Please feel free to share your valuable comments below and do subscribe to our newsletter for more tips and information on everything aquariums!


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