Reef Tank Algae Turf Scrubbers – What Are They?

Is algae taking over or causing problems in your saltwater aquarium? As an aquarium hobbyist, I’m sure you would agree that you want your fish and coral to stay happy and most importantly healthy! Over the last few years, these devices called Algae Scrubbers or Algae Turf Scrubbers have appeared, but many people have no idea what they do.

Algae scrubbers are aquarium filters that use light to rapidly grow algae to filter the water, consume harmful chemical compounds, and help keep aquariums algae-free. The Algae is harvested by the owner as it grows and this removes the pollutants absorbed within it.

Excess algae in your aquarium is a leading cause of water quality issues that could potentially kill your corals and fish. Not only that, algae looks terrible! By growing algae in a controlled environment, these devices allow your aquarium to stay clean & healthy.

What Is an Algae Scrubber?

An algae scrubber is a purpose-built vessel that allows aquarium water to run through it. As the water passes through the device, high-intensity LED lights with a wavelength designed to promote plant growth are shone into the water. This creates an environment perfect for growing algae.

As the algae grows, the aquarium owner opens the filter housing during regular tank maintenance and disposes of the mat of algae that has grown. By disposing of the algae, the owner has helped to remove nuisance nutrients like nitrates, nitrites, and phosphates from the aquarium which are the main food for algae to grow but, at high enough levels can not only stunt coral growth but also cause livestock death.

As the algae grows within the scrubber it helps keep the algae contained so that it prefers to grow in the scrubber, rather than in the aquarium. A simple but very effective device!

What Does An Algae Scrubber Do For The Aquarium?

Algae scrubbers act as a natural water filter to remove nitrate, phosphate, and other harmful pollutants. They create a controlled setting to allow algae to rapidly grow, away from your aquarium.

In addition to preventing algae growing in your aquarium, they also help to stabilize the pH due to an increase in gas exchange as the water flows through them. Oxygen is absorbed into the water and nitrogen and carbon dioxide are released and consumed by the algae as it grows.

If you have a lot of corals in your aquarium, adding an algae scrubber will promote rapid, colorful, healthy growth.

How Does An Algae Scrubber Work?

They are pretty simple, and there are two types:

  1. Waterfall Scrubber – Water is pumped directly into the top of the scrubber and allowed to naturally fall over a rough-surface screen. The water is then removed from the scrubber via a drainage system, and returned back into your aquarium via gravity.
  2. Upflow ScrubberThe upflow uses air. The cavity is filled with water and air is pumped in at its base to create a current. The algae then grows on proprietary capture materials from which the algae can be harvested.
The Inside of a ‘Waterfall’ Type Algae Scrubber

A safe, high-power LED light system containing two spectrums of either red or blue light are installed inside or on the side of the scrubber to encourage algae to grow rapidly. This is important, as the faster the algae grow, the more nuisance nutrients are removed from your aquaria.

There are many models to choose from with both external or internally mounted algae scrubbers. As the name suggests, the external algae scrubber sits outside the sump, normally above it.

If space is at a premium or your aquarium does not have a sump, you can go for an internal or hang-on scrubber. These types of algae scrubbers sit on the side or inside the tank or sump and water or air is pumped through the scrubber to create a water flow for the algae to constantly receive the nutrients it needs to grow.

After installation, it usually takes around 4 weeks for the algae to build up. Most scrubber owners remove the screen every 7-14 days to clean it, depending on how much algae is produced. The algae grows in a mat on the screen or capture material and once it builds up to around ¼ to ½ an inch thick, it’s time for harvesting and disposal.

The most common methods of control are to run the light on a plug-in timer. In the beginning, it is recommended to run it 24/7 to allow the algae to build up. Once the unit has ‘Broken In’ most aquarists run them on the opposite cycle to their main aquarium lights – ie, run the scrubber during the night.

By doing this it helps to stabilize the fluctuations in Ph caused by the lack of organisms awake during the hours of darkness.

Which Algae Scrubber Is Best For You?

There are many different types and they all range in size, so selecting the one that best suits your aquarium size is easily accomplished. However, when comparing which scrubber to buy, also consider how much food you feed your fish in your aquarium, what is the quality of your source water, and how much algae are you currently getting in your tank.

The more excess nutrients you have in your water, the more algae your aquarium grows. There is no such thing as ‘over-scrubbing’ but having a larger algae scrubber will allow more algae to be filtered from the aquarium.

The trick is to find the balance of scrubber size and price. The larger the algae scrubber, the more it costs. On each of the algae scrubbers shown in the links below at Marine Depot, they list both the recommended size tank for each scrubber and the water or air pump needed for each type.

Here are a few of the best-rated algae scrubbers:

IceCap Algae Scrubber

These are fully enclosed, easily installed, and made from top quality acrylic and PVC. The lighting system is powered by IP66 waterproof LED lights and the adjustable spray bars make them operate quietly.

It is recommended to be installed above the sump so water can flow back via gravity. An awesome feature is that it has an emergency drain fitting if your main drain were to become clogged with algae.

They are available in 3 sizes from

External Use Only and require a feed pump and additional plumbing.

Santa Monica RAIN Algae Scrubber

The RAIN series has lights that can be fully submerged, so it does not take up much space around your tank or sump.

It can also be mounted on a pole attachment (sold separately) to suspend the scrubber above the water for easier cleaning and have it drain via gravity.

They are available in 2 sizes:

  • Small – RAIN2 For aquariums 10 – 40 Gal
  • Medium – RAIN4 For aquariums up to 55 – 300 Gal

Multiple scrubbers can be used to filter any sized tank.

Submerged or Above Water Installation Only and requires a water pump and additional plumbing.

Santa Monica HOG Algae Scrubber

The HOG or Hang-On-Glass series is an ‘Upflow’ Scrubber.

It consists of two halves. The LED half sits on the outside of the glass, while the growth half sits inside the sump or tank. The two halves are magnetic.

Air is fed into the base of the growth side to create the water flow required. These are perfect for those who wish to install them behind rock of an aquarium with no sump.

They are available in 2 sizes for saltwater:

  • Small – HOG3 Series for aquariums 5 – 10 Gal
  • Medium – HOG3xx Series for aquariums up to 10 – 40 Gal

Multiple scrubbers can be used to filter any sized tank.

Air pump required. Each model specifies which size air pump is required.

Santa Monica SURF Algae Scrubber

The SURF series is an ‘Upflow’ Scrubber.

The foam pad floats on the top of the water and air is pumped into its base. As the bubbles rise up the algae capture material, it moves the water with it, causing the algae to grow.

These are meant for sump installations where the scrubber can float out of sight of the main aquarium. The light is easily removed from the top to allow for single-handed harvesting of the algae.

They are available in 7 sizes:

  • Small – SURF2 Series for aquariums 10 – 40 Gal
  • Medium – SURF4 Series for aquariums up to 55 – 120 Gal
  • Large – SURF8 Series for aquariums up to 55 – 300 Gal

Multiple scrubbers can be used to filter any sized tank.

Air pump required. Each model specifies which size air pump is required.

Santa Monica DROP Algae Scrubber

The DROP series is an ‘Upflow’ Scrubber.

The compact compartment sits fully submerged and is great for hiding away in the back corners of an aquarium or sump.

Air is fed into the top of the scrubber and channeled to the base. A special cradle allows this series to sit on the sandbed without sand being pulled into the scrubber.

They are available in 2 sizes for saltwater:

  • Small – DROP1.4 Series for aquariums 5 – 10 Gal
  • Medium – DROP1.4x Series for aquariums up to 10 – 40 Gal

Multiple scrubbers can be used to filter any sized tank.

Air pump required. Each model specifies which size air pump is required.

Find the Complete Santa Monica Range of Algae Scrubbers Here at

To Finish

Fitting this simple device to your reef tank could allow you to finally be free of that constant algae plague you have been battling for months. A simple light-filled compartment that allows the algae to grow out of sight may be all that is required, and these scrubbers do just that.

They are all designed to be harvested and cleaned quickly and with ease allowing the nuisance nutrients to be removed and more algae can be grown to repeat the process.

By ensuring you size the scrubber to suit your tank size and current algae growth rate you will find that you are cleaning your glass less and your water quality improves!


Hi, I'm Richard and I have been an avid aquarist for over 30 years with a passion for Saltwater Aquariums. I love to pass on my knowledge to help others get the same amount a pleasure out of this hobby as I do. View my About Me page to find out more about me & my mixed reef aquarium.

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