"Stoutman" .@. wrote in
m:

I am not sure what you mean by "make it harder", but if you are
implying that high NH3 levels kill the nitrobacter than what is the
ED50 for this? Furthermore, is the ED50 less than the maximum
concentration of NH3 that is normally reached during cycling? Is this
something you found out after doing some research on your own? Heehee
hee heee, snicker!

I've heard this claim before--Wayne Sallee did not just pull it out of his
ass through personal or unscientific observation. I believe there is
research out there to back it up.

I am uncertain myself if there is a direct relationship between the levels
of free ammonia and the efficacy of nitric bacterium or an indirect one in
which the relationship is as simple as the fact that the conversion of
nitrite into nitrate requires more oxygen and more energy than the
conversion of ammonia into nitrite and therefore nitrous bacterium have
easier access to available oxygen. Hopefully the previous poster can
produce some referenced material to clear this up.

Btw... according to recently published research done by Tetra the long held
believe that nitrosomonas and nitrobacter are the main bacteria responcible
for the nitrogen cycle in aquaria is false. Tetra research found that
bacteria belonging to completely other sets are doing the bulk of the work,
namely Nitrosococcus and Nitrospira.

Here's a link: http://www.marineland.com/science/nspira.asp