Originally Posted by Raul-7
It is well known from documented research papers that the nitrifying bacteria operate at close to 100% effectiveness at a pH of 8.3, and this level of efficiency decreases as the pH lowers. At pH 7.0 efficiency is only 50%, at 6.5 only 30%, and at 6.0 only 10%. Below 6.0 the bacteria enter a state of dormancy and cease functioning. Fortunately, in acidic water (pH below 7.0) ammonia automatically ionizes into ammonium which is basically harmless.
In the "normal" nitrification cycle, 7 carbonate molecules are consumed for each molecule of ammonia processed to nitrate. For this reason, active biological filters need carbonate in the water to function efficiently.
Temperature also affects the rate of growth of nitrifying bacteria.
Biological filtration is more efficient in warm, base rich conditions, but those figures for the lower rates of biological filtration at lower pH are based upon the assumption that the filter organisms involved in microbial filtration in aquariums are the same bacteria that you find in waste water treatment.
More recent research, using RNA markers, has shown that the nitrifying organisms in aquarium filters (and low ammonia situations in nature) are mainly from the Archaea and that they have a much wider range ecological tolerances.
Dr Hovanec's original research was focused on Nitrobacter, Nitrosomonas and Nitrospira
and of these we now know that only the last is a major player in aquariums.
"Freshwater Recirculating Aquaculture System Operations Drive Biofilter Bacterial Community Shifts around a Stable Nitrifying Consortium of Ammonia-Oxidizing Archaea and Comammox Nitrospira".
"Ammonia-oxidizing archaea have more important role than ammonia-oxidizing bacteria in ammonia oxidation of strongly acidic soils".
"Temporal and Spatial Stability of Ammonia-Oxidizing Archaea and Bacteria in Aquarium Biofilters".