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TomCs
10/18/2009, 12:10 AM
Is there any form of Nitrogen fixation that occurs in the typical reef tank? Ammonium ions from waste products mark the start of the cycle with it ending in N2 (NH3orNH4-, NO2, NO3, N2 and N2O). Does much of this N2 become reintroduced to the tank if fixation does somehow occur in an aquarium. Im new to all of this and so apparently cyanobacteria are capable of nitrogen fixation? If that is true do they contribute to unusually high nitrate levels? Also is iron concentration considered important in reef tanks as a high concentration may cause an increased amount of nitrogen fixation by cyanobacteria and alike...
Sorry if i have this process completely wrong just starting out in marine chemistry and am just interested in how it translates in to our hobby.

Randy Holmes-Farley
10/18/2009, 07:01 AM
Cyanobacteria can fix nitrogen, so it potentially cannot be eliminated by complete removal of ammonia, nitrite and nitrate.

Bear in mind that the atmosphere is 70% N2, so there is lots of it in reef tank water and there is no way to eliminate it from a tank, and minor additions of N2 from denitrification do not impact total N2 much.

Many organisms use iron, although that by itself does not imply that an additive is necessary. Nevertheless, macroalgae does often respond positively to iron. It is possible that iron additives may boost cyano.


These have more:

Ammonia and the Reef Aquarium
http://reefkeeping.com/issues/2007-02/rhf/index.php
Nitrite and the Reef Aquarium
http://reefkeeping.com/issues/2005-06/rhf/index.htm

Nitrate in the Reef Aquarium
http://www.advancedaquarist.com/issues/august2003/chem.htm

The Complete Nitrogen Cycle
http://web.archive.org/web/20030510131423/http://www.animalnetwork.com/fish/library/articleview2.asp?Section=Aquarium+Frontiers+--+Biochemistry+of+Aquaria&RecordNo=3090
First Iron Article: Macroalgae and Dosing Recommendations
http://www.advancedaquarist.com/issues/aug2002/chem.htm

Second Iron Article: Iron: A Look at Organisms Other than Macroalgae
http://www.advancedaquarist.com/issues/oct2002/chem.htm

tatuvaaj
10/18/2009, 08:36 AM
Interestingly, Acropora spp. (and some other other stony corals) can also utilize N2 with the help from symbiotic cyanobacteria: http://www.springerlink.com/content/h268q7357196753l/fulltext.pdf

HighlandReefer
10/18/2009, 09:02 AM
Thanks for the link Tatu. :)

The organisms in a reef tank that can utilize nitrogen fixation continues to be discovered by scientists. Research has shown that many algae in addition to bacteria & cyanobacteria can utilize nitrogen fixation. This is not to say that all algae, bacteria, cyanobacteria and coral can utilize nitrogen fixation, it will depend upon the specie. ;)