Question on nitrifying bacteria

[Ingen]

I remember vaguely reading online that anything below PH of 5.5-6 may have a negative impact on the nitrifying bacteria or rather they may not even survive. Does it mean that tank with low PH does not have nitrifying bacteria to convert ammonia?

[Urban Aquaria]

There are still nitrifying bacteria at lower pH conditions, just that its much less than at higher pH conditions... on the flip-side, ammonia is also in its less toxic form at lower pH conditions, so it sort of evens out.

The most important thing with low pH tanks is not to do anything which shift the pH higher too quickly (ie. large water changes, dosing buffers), as the ammonia will quickly turn back into its toxic form while the nitrifying bacteria are still not able to handle it yet as they need time to grow.

[Ingen]

I see, that make total sense.

[Ingen]

Would it also mean that the end product nitrate will be lower too?

[Urban Aquaria]

Would it also mean that the end product nitrate will be lower too?

Well, the end product of nitrate would still be the same amount... just that the nitrification process in lower pH conditions is less efficient and slower, so it takes more time for the ammonia to be converted to nitrite and then to nitrate.

Plants can consume ammonium though, so a high density of fast growing plants can soaking up excess ammonium in a tank (before it even gets processed), therefore those plants can help reduce the processing load of the nitrifying bacteria.