Algae Scrubber

An algae scrubber is a water filtering device (not to be confused with a scrubber pad used to clean glass) qui uses light to grow algae ; In this process, undesirable chemicals are removed from the water. [1] Algae scrubbers allow saltwater and freshwater aquarium and pond hobbyists to operate their tanks the way that oceans and lakes operate by using natural filtration in the form of primary production .


Both iron fertilization and ocean nourishment are technical That boost the primary generation of algae in the ocean, qui consumes massive water equivalent of nutrients and CO 2 . It is this same consumption of nutrients that algae perform in an aquarium or pond.

An algae scrubber filters water by moving water rapidly over a rough, highly illuminated surface, which causes a large increase in growth. As the algae grow, they consume nutrients such as nitrate , phosphate , nitrite , ammonia , ammonium and even metals such as copper from the water. [2] These nutrients are normally a problem in aquariums and because they cause nuisance to grow, and also because they cause sickness and / or other problems in fish aquarium, invertebrates and corals. [3]An algae scrubber allows algae to grow, but the algae grow inside the filter instead of in the aquarium or pond. This removes excess nutrients (scrubs the water), diminishing nuisance algae in the aquarium or pond. Nuisance algae in the aquarium or in the algae scrubber filter itself. The algae that grow in the algae scrubber can then be removed, or fed back to the livestock.

Algae scrubbers are used in both saltwater and freshwater, and remove algae nuisance of multiple types: cyano or slime , bubble , hair , Chaetomorpha , Caulerpa , and algae film , as well as dinoflagellates and Aiptasia .


The Algae Scrubber was invented by Dr. Walter Adey , who was born in the late 1970s, was Director of the Marine Systems Laboratory at the Museum of Natural History, Smithsonian Institution (Washington DC, USA). [4]His research of various types of algae, especially in their ecological role on coral reefs, gave him insight into how the ocean (in particular a reef) “recycles” nutrients. It has been designed and constructed in different sizes and has a different hydrangea than other tropical water systems. It has a tropical coral reef / lagoon which, after 8 years of closure, has had its chemical parameters controlled by an algal turf. This system, studied by a multidisciplinary team of biologists, shows calcification [coral growth] rates equal to the best 4 percent of wild reefs, and at 543 identified species, and an estimated 800 species, ranked as one of the most biodiverse species. reef ever measured. ” [5]

In his editions, Dynamic Aquaria, Dr. Adey described his work in a physical, chemical, and biological considerations for building an ecosystem, from an aquarium size, to microcosm (up to 5000 gallons), gold mesocosm size (> 5000 gallons). In describing the algal turf scrubber he designed, he explained that removing excess nutrients was not only its function. By operating the scrubber at a time when the body has been absorbed by a different phase of the body, it has been absorbed by the oxygenated membrane.

“Recycling” means how nutrients go from plants to animals, and back to plants again. On land, you see the following: Green plants use carbon dioxide and release oxygen; use this oxygen and release carbon dioxide. In oceans and lakes, the nutrients go algae to animals, and back to the algae again.

Dr. Adey built several versions of algae scrubbers for aquariums at the Smithsonian. He called them “Algal Turf Scrubbers”, because it was believed that “turf” was the best type of algae to grow in a scrubber. He was granted the first US patent for dumping-bucket algae scrubber, [6]which has a complex dumping effect on a horizontal surface, thus simulating waves in a reef environment. After several years of development, he participated in a large algae scrubber on the Great Barrier Reef Aquarium: “The Reef Tank represents the first application of algal scrubber technology to large volume aquarium systems. filters) have had a high level of nutrient levels in millions, while algal scrubbers have been maintained in concentrations of much higher concentrations in the water. in the observed spawning of scleractinian corals and many other tank inhabitants. ” [1]

Unfortunately, it was not known at the time (1988) that the calcium and alkalinity needed to be added to an enclosed reef tank, which is used by growing calcifying organisms. Even if the Pittsburgh Zoo was just starting to test a “mesocosm” scrubber reef tank to see if calcium levels would drop: “It was hypothesized that Ca 2+ and the substitutive elements Sr 2+ and Mg 2+might have reduced concentrations in a coral reef microcosm due to continuous reuse of the same seawater as a consequence of the recycling process inherent in the coral reef mesocosm. “[…]” The scleractinians (Montastrea, Madracis, Porites, Diploria, and Acropora) and calcareous alga (Halimeda and others) present in the coral reef mesocosm are the most potent responsible for the significant reduction in concentration of the Ca 2+ and Sr 2+ cations. “[…]” Ca is not normally a biolimiting element, and strontium is never a biolimiting element; HCO 3[alkalinity] can be. It appears that, because of a minor limitation in the design parameters of the mesocosm, these elements and compounds may have becoming limiting factors. […] ” [7] After the researchers added calcium and / or connected their tanks and nutrients (ammonia, ammonium, nitrate, nitrite, phosphate, CO 2 , metals) have been kept at very low numbers.

Dr. Adey licensed to the world, who has a limited number of years of aquarium scrubbers to hobbyists. The complexity of the design, however, and the cost of the license, caused the scrubber units to be very expensive. This, combined with the fact that the units were noisy, splashy, and unreliable (the dumping mechanism would get stuck) caused the sales to be slow. The scrubbers were just starting to make the aquarium hobby in the 1990s when it was possible to buy them. He turned his attention to commercial and industrial applications, and entered private business making large scale scrubber facilities for lakes and rivers. [8]

As the internet developed in the 1990s, aquarium and pond hobbyists began discussing nuisance algae problems, and started noticing a trend: Aquariums and ponds avec les nuisances de nuisance algae. This at first seemed odd, since the amount of nuisance algae should increase the nutrients in the water increased. How could there be a large amount of nuisance algae, but no measurable nutrients in the water to support this? Biologists then began to point out that when the amount of algae nuisance became large enough, the algae actually consumed all the nutrients from the water faster than new nutrients were added. Dr. Adey’s principles were at work again.

Interest in using algae for nutrient control still increased, this time in the form of keeping the aquarium in a “sump” or other small aquarium which is connected to the aquarium via plumbing. With added lighting and flow, algae would grow in this area, and the algae would consume nutrients from the water just as Dr. Adey’s algae scrubber units did. Sumps or other small aquariums used for this purpose have become known as “refugiums”. [9]The name “refugium” has been used because it has grown to be a “safe haven” and it has been “safe” from the large fish and invertebrates in the aquarium that would otherwise consume them. However while the refugiums did not consume nutrients from the water, they did not consume them fast enough in all situations; this caused many hobbyists to continue to have nuisance algae problems in their aquariums hand.

Modern forms

More recent variations are built with a simple “waterfall” driven by gravity, using a simple PVC plumbing pipe to flow water down to a piece of plastic knitting screen (also known as “plastic canvas”), which is roughed up to allow algae to attach . In almost every case, these problems have been reduced to very low levels, and this reduced or eliminated all nuisance algae problems.

In addition, “turf” algae, which was the focus of Dr. Adey’s dumping-bucket design, is replaced by “green hair algae”. [10] This is because of the darkness of the clouds and the darkness of the clouds. This slows the growth (and filtering) of the algae because of the bottom layers of algae that are attached to the screen start to die and detach. Green algae, however (especially light-green hair algae), allows light and water to penetrate all the way down to 20 mm thick, [11]which allows you to grow faster and absorb more nutrients without dying and losing attachment to the screen. This is fortunate because green hair is the exact type of algae that grows in a properly constructed algae scrubber.

Some models also use up-flowing air bubbles. This version, which is essentially the opposite of the waterfall, allows the algae to be placed underwater in the aquarium, sump or pond, instead of above it. This greatly simplifies construction, since it does not allow for waterproofing, and it allows placement of the scrubber into tight areas where there is no room for water. The design also keeps the algae from drying out in the event of a power failure, because all the algae is under water, and the design also removes almost all splashing. The up-flowing bubble design falls into three categories: those that attach to and shine through the aquarium (or sump) glass; those that float on the top of the aquarium, sump or pond water surface; and those that go completely underwater like a submarine.

Cleaning and harvesting

Generally, and except for specific continuous-filtering or continuous-cultivating versions, algae scrubbers require the algae to be removed (“harvested”) periodically from the scrubber. This removal of algae has the effect of removing nutrients from the water because of the use of nutrients in order to grow. The algae is generally removed either:

  • Every 7 to 21 days, gold
  • When it is black, gold
  • When it fills up the scrubber, gold
  • When it starts letting go, gold
  • When nutrients start to rise in the water.

For waterfall versions, the screen is removed from the pipe and cleaned with running water. The pipe is removed, and the slot is cleaned with a toothbrush, to remove any that has grown up into it. After the algae are removed, the screen and the pipe are back in the scrubber. For upflow versions, the cleaning method depends on the type:

Glass-attached version: The magnet portion is removed from the glass, and the inside portion is lifted out of the water. If the growth is thick green hair, then it is just removed by hand. If the growth is thin green hair (as occurs in freshwater) or dark slime, then the inside unit is taken to the sink and cleaned with a toothbrush. After cleaning, the inside and outside parts are put back into place on the glass.

Floating-surface version: If the growth is thick green hair algae then it is just removed by hand lifting the LED lid up and pulling the growth out. If the growth is thin green hair or dark slime, then the floating portion is taken to the sink and cleaned with a toothbrush.

Drop-in version: The entire unit is lifted out of the water, and the lid is removed. If the growth is thick green hair then it is just removed by hand. If the growth is thin green hair or dark slime, then the whole unit is taken to the sink and cleaned with a toothbrush.

If the screen is not cleaned like this periodically, the algae will get too thick and block light and reach the “roots” of the algae, and these areas will die and let go, putting nutrients back into the water. [10]

See also

  • Refugium (fishkeeping)
  • Wikiversity: Algae scrubber , on how to build a DIY algae scrubber


  1. ^ Jump up to:b Nutrient Cycling In The Great Barrier Reef Aquarium. Proceedings of the 6th International Coral Reef Symposium, Australia, 1988, Vol. 2
  2. Jump up^ Algal Response To Nutrient Enrichment In Forested Oligotrophic Stream.Journal of Phycology, June 2008
  3. Jump up^ Fish Disease: Diagnosis and Treatment, Second Edition, 2010
  4. Jump up^ Smithsonian Institution, Dept. of Botany
  5. Jump up^
  6. Jump up^ US Patent 4333263, Issue Date June 8, 1982
  7. Jump up^ An Introduction to the Biogeochemical Cycling of Calcium and Substitutive Strontium in Coral Reef Living Mesocosms
  8. Jump up^ Hydromentia Water Treatment Technologies
  9. Jump up^ Reef Invertebrates, 2003, page 46
  10. ^ Jump up to:b AlgaeScrubber.Net
  11. Jump up^ Production in dense mats of the filamentous macroalga Chaetomorpha linum in relation to light and nutrientavailability, Figure 5.

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