Everything We Know About Bacteria Is Wrong?

This is a page detailing current knowledge of nitrifying bacteria, gleaned from scientific papers on nitrifying bacteria in both waste water management and aquarium systems. I’ll summarise...

1. The optimum level of ammonia for nitrifying bacteria is 400ppm. The upper limit is 2750ppm.

2. The optimum level of nitrite for nitrifying bacteria is 200ppm. The upper limit is 7500ppm.

3. Nitrifying bacteria need at least 80% oxygen saturation to thrive. Because of this, 80-84% of these bacteria reside in the filter. In a very clean, well filtered aquarium this proportion is even greater.

4. Nitrifying bacteria will survive for several years without food. They only need water and oxygen to survive.

5. Nitrifying bacteria colonies do not grow to a size governed by the bioload/amount of ammonia available. Since they don’t need to eat to survive, the colony continues to reproduce with the ammonia produced by fish. They will only stop reproducing if zero ammonia is available to them.

6. The brown ‘mulm’ that accumulates in a filter should not be removed (unless absolutely necessary to preserve water flow). It is full of bacteria, archaea, flagellates, ciliates, microscopic worms, and many other organisms. This mulm is largely composed of  extracellular polymeric substances (EPS) secreted by the bacteria that house these organisms.

7. Nitrifying bacteria do not need KH. In even a very heavily stocked aquarium they get all the carbon they need from carbon dioxide.

8. There’s no such thing as a ‘bacterial bloom’ in the water column. These are in fact blooms of infusoria, feeding on heterotrophic bacteria.

9. Nitrifying bacteria cannot use ammonium (NH4-). This is why nitrification slows down in acidic water and stops at pH6, because ammonium is virtually non-existent at pH6.

Point #6 is interesting.
It is often said that a lot of the brown stuff in a filter is fish poop, uneaten food, bits of dead plants etc which decompose to make ammonia, which is then processed into nitrate. A lot of goo in the filter contributes to high levels of nitrate in the tank. Therefore the goo should not be allowed to accumulate.
Yet point #6 says the goo is good and should not be removed.

Which is right?


Points #1 and #2 sound like the early days of research into aquarium flora and fauna (I use the words flora and fauna fauna to mean bacteria plus all the other micro-organisms). I know that the initial work on bacterial starters used data from waste water management systems where the levels of ammonia and nitrite are a lot higher, and this led to the use of the wrong species of nitrite eaters in the early days.
Is there now evidence that these higher level ammonia and nitrite micro-organisms do grow in aquariums?

I skimmed through the article I'm afraid  but on slower reading:

I'd never heard the one about 9 ppm nitrite inhibiting nitrite eaters. I had always read that at 15 to 16 ppm, it slowed down the multiplication of them so much that the cycle stalled - it became very slow.





Lots of people think that when the water in a new tank goes cloudy it means the bacteria are growing and the cycle has started. I always correct this when I read it.




I prefer to use the terms ammonia eaters and nitrite eaters rather than bacteria. I know technically they don't 'eat' anything but the terms do allow for other micro-organisms than just bacteria. Though I have been known to use 'bacteria' as shorthand.

@fcmf, your post prompted me to delve a little deeper into the site (I’ve been busy today), and I now have to agree that most of what he is saying is downright ridiculous. He argues against just about everything we know to be true (and backed up by an immense amount of scientific proof).

I was a little sceptical about his information to start with because he provides no links to any of the “scientific research papers” he mentions. But I ploughed on regardless. More fool me.

Ignore it all guys, it’s all rubbish.