Saltcorner
By Bob Goemans
By Bob Goemans
Dear Bob,
What are your thoughts on algae filtration for the freshwater setup as opposed to the bacterial filtration that is common today? I have heard that in the oceans, rivers, lakes and streams in nature are filtered with algae and not bacteria. If we strive to duplicate nature in our homes (If algae is what nature uses) why aren't algae filters or "algae scrubbers" the norm instead of bacteria based filters?
And if algae scrubbers are so great, why aren't more companies competing to make these things more available to the average consumer. I have yet to see an algae scrubber available for sale in my local fish stores?
Thanks,
Deon
Hi Deon,
This is a method that allows water from the aquarium to flow through an area containing a heavy growth of algae. The algae remove dissolved "inorganic" nitrogen compounds (ammonia, nitrite, and nitrate) and various other elements. Since the algae actually use the nitrogen for growth after reducing it to ammonium, and produce oxygen and remove carbon dioxide during this process, excessive nitrogen can efficiently be removed from the aquarium by simply harvesting excess algae on a periodical basis. This differs from biological filtration where bacteria consume oxygen and produce carbon dioxide while reducing nitrogen products to less toxic forms of nitrogen and finally discharging them as nitrate, an algae nutrient, back into the surrounding waters.
As good as this filtration method may sound, there are some possible drawbacks. Since the algae are housed in a separate container, it is like having two interconnected aquariums. One to contain the algae and one to house the fishes and invertebrate. Not only does the aquarium containing the fish and invertebrate require lighting, the unit that houses the algae must also be lighted. Water flow through the algal scrubber unit must be somewhat turbulent to aid assimilation of surrounding nutrients, thereby enhancing their growth. Even though the water in the entire system may remain nutrient poor when it comes to inorganic nitrogen and phosphate compounds, it may become rich in organic nutrients.
Also, heavy growth of algae compete all too well for the same nutrients that coral zooxanthellae utilize, possibly affecting long term coral growth. The algae also leach organic compounds that result in a yellowing of the water. Colored water affects spectrum and intensity of light, possibly also affecting coral growth. Since the founders of the Algal Turf Scrubber process did not utilize or recommend use of protein skimming, activated carbon, or the use of additives, system results were and still remain a subject of intense controversy. Anyone interested in more information concerning this method should read the "Dynamic Aquaria: Building Living Ecosystems" by Adey and Loveland (ISBN 0-12-043790-2).
Hope this helps,
Bob Goemans
