The nitrogen cycle in low pH water?

[Eddiekay1010]

Was reading about the nitrogen cycle and read that bacterial growth ceases at a pH of 6 and below. A few questions came to mind,
1- If your trying to breed a fish from a area with an extremely low pH, do you have to worry nitrite spikes. I know that ammonia isn't toxic in acidic conditions, but can you have nitrites with a non-toxic form of ammonia coming first?
2- How does it work in the wild?

 

[MacZ]

1. The cycle is mostly taken over by archeans, fungi and yeasts. They are already there in higher pH. The cycle does not immediately crash with low pH, as many people think.
2. Same. Plus in the wild in many biotopes the water is not stagnant but has at least some flow. Basically constant fresh water, also from daily rains in the rainy season. At least in the Amazon basi and other parts of South America and many waters in Afrika, where dwarf cichlids come from. It can happen that fish get trapped in small pools in the dry season. But there temperature and lack of oxygen kill off a lot of fish. pH is secondary then.
Extremophiles like licorice gourami from South East Asia live in standing puddles and peat bogs in the wild, they need pH even lower than many blackwater Apistogramma. Just read a breeding report stating the species needed a pH below 3!
But pH is not everything anyway.

 

[dw1305]

Hi all,

Was reading about the nitrogen cycle and read that bacterial growth ceases at a pH of 6 and below.

Probably read something else, that <"one is definitely wrong">. On UKAPS we were lucky enough to some input by Dr Tim Hovanec recently, <"which maybe of interest">.

In fact nearly everything you read about "cycling" and "nitrification" on forums (and are told by LFS) is wrong, and <"is based on research that has been totally superseded by more recent scientific advances">.

1- If your trying to breed a fish from a area with an extremely low pH, do you have to worry nitrite spikes. I know that ammonia isn't toxic in acidic conditions, but can you have nitrites with a non-toxic form of ammonia coming first?

Yes and no, NO2- is still really toxic, but after that it is back to the microbes that actually occur in aquarium filters.

We now know that ammonia oxidising archaea (AOA) are the major players in the conversion of ammonia/ammonium (NH3/NH4+) to nitrite (NO2-) and that they form a stable assemblage with Nitrospira spp. some of which are cannonical nitrite oxidisers, and some of which are COMAMMOX organisms that can directly convert ammonia to nitrate.

How does it work in the wild?

Ammonia Oxidising Archaea look to be pretty much universal in natural situations. You also <"have plants"> and plant/microbe nitrification is much more efficient than "microbe" only nitrification.

cheers Darrel