I had just reviewed this thread and I had prepared a follow up on the sandbed article.
From Ammonium to Nitrogen
As previously stated, in a zone which is totally anaerobic, ammonium will be produced rather than nitrogen gas. This can be a problem as ammonium is a very good fertiliser for nuisance algae.
But recent research conducted in the Black Sea found that bacterium from the order Planctomycetales is able to convert ammonium to nitrogen gas together with nitrite.
This process termed Anammox stands for anaerobic ammonium oxidation. Nutrient profiles, fluorescent RNA probes, 15N tracer experiments and the distribution of specific "ladderane" membrane lipids show that the ammonium that is diffusing upwards is consumed by anammox bacteria just below the aerobic zone.
This shows that anammox actually plays a part in the Nitrogen Cycle in the sea and occurances in captive systems is a new field that is worth researching. By showing how deeper sandbeds can actually be a zone for the colonisation of anammox bacteria might just unlock a new methodology for sandbed keeping and who knows what benefits it can hold?
Next up will be a follow up on the black substance usually found in sandbeds so stay tuned!!
The above information about anammox bacteria are from nature publishing group, www.nature.com