Low pH and denitrification

[koty]

I am keeping my aquarium (planted) with a constant pH around 4.7 (R/O + acidic peat extract). Many places on the www claim that bacterial de-nitrification (ammonia oxidation to NO2 and NO3) virtually cease to exist.
I personally do not believe it based on my basic knowledge on bacteria that there is a bacteria for any possible substrate and condition.
Before I bother to renew my ammonia detection kit I was wondering if anybody can comment.
thanks
koty

 

[beleg]

Ammonia is not poisonous in lower pH levels if i recall correctly. Besides plants can utilize Ammonia as well.. Most plants however wont do well in a very acidic extremely soft water environment.

 

[Refael Hdr.]

Hi koty,
From my own experience I can tell that I'm keeping my planted tank with pH of about 5.6 (+- day and night minor changes). At first I could obviously notice that the ammonia levels are very high for a long period of time, much more than in a regular new setup with a neutral pH.
The only reason that the fish, especially the delicate ones, could survive in this levels was due to the fact that in this low pH the toxic ammonia forms the state of ammonium (NH4+) that is much less toxicant.
After a while I could see a gradual decrement of the ammonium levels (than followed by nitrite decrease of course) until it couldn't be detectible anymore by my lab test kit.
From this I could only conclude that in lower pH the regular nitrifying bacteria are being replaced by another type of bacteria that can live and metabolise naturally in these conditions. Though this supersession is taking some time. In addition I think that the cycle activities are regularly much more slow lasting in this conditions...