Algae scrubber

[1] Algae scrubbers allow hobbyists to operate their saltwater or freshwater tanks or ponds using natural filtration based on primary production, much as occurs in oceans and lakes.

As the algae grow, they consume nutrients such as nitrate, phosphate, nitrite, ammonia, ammonium and even metals such as copper from the water.

The algae scrubber was invented by Dr. Walter Adey, who beginning in the late 1970s, was Director of the Marine Systems Laboratory at the Museum of Natural History, Smithsonian Institution (Washington DC, USA).

He designed and built various exhibits ranging in size up to 3000 gallons, and modeled different aquatic ecological systems including a tropical coral reef/lagoon which "after 8 years of closure [to the environment], had its chemical parameters controlled solely by an algal turf scrubber.

"[5] In three editions of his book, Dynamic Aquaria, Dr Adey described his work in detail and discussed in scientific principles the physical, chemical, and biological considerations for building a functioning ecological system within an enclosure, from aquarium size, to microcosm (up to 5000 gallons), or mesocosm size (>5000 gallons).

By operating the scrubber at night when the main tank had shifted to a different respiratory phase (plants were now absorbing oxygen rather than producing it) the scrubber maintained oxygen levels and helped buffer pH by preventing high levels of carbon dioxide from building up.

He also was granted the first U.S. patent for a dumping-bucket algae scrubber,[6] which described a complex dumping device that poured water onto a horizontal surface, thus simulating waves in a reef environment.

"[1] Unfortunately, it was not known at the time (1988) that calcium and alkalinity needed to be added to an enclosed reef tank, in order to replace that which is utilized by the growing calcifying organisms.

[...] "The scleractinians (Montastrea, Madracis, Porites, Diploria, and Acropora) and calcareous alga (Halimeda and others) present in the coral reef mesocosm are the most likely organisms responsible for the significant reduction in concentration of the Ca2+ and Sr2+ cations."

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.

He turned his attention instead to commercial and industrial applications, and entered private business making large scale scrubber installations for lakes and rivers.

This version, which is basically the exact opposite of the waterfall, allows the algae scrubber to be placed underwater in the aquarium, sump or pond, instead of above it.

This greatly simplifies construction, since the device does not need to be waterproof, and it allows placement of the scrubber into tight areas where there is no room above the water line.

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.

If the growth is thin green hair or dark slime, then the floating portion is taken to the sink and cleaned with a toothbrush.