Hi all,
I never answered this bit, my guess is that you are right and the plants mop up most of the ammonia before it makes it into microbial nitrification. In a non-planted tank you have a few other variables that become more important.I know plants play into this as I guess in a heavily planted tank the ammonia rarely makes it to nitrification and is consumed by the plants before then. How would this differ in a non planted tank?
- The first is the level of dissolved oxygen, if you <"can get enough oxygen into the water"> you can potentially microbially oxidise a much larger amount of ammonia. Some types of filter (particularly "wet and dry" trickle filters) are more effective at maintaining oxygenation.
The prime metric in nitrification isn't actually the ammonia concentration, it is the dissolved oxygen level. As you have water with greater amounts of organic pollution its Biochemical Oxygen Demand (BOD) increases, BOD values range from clean water at below 5 mg/l dissolved oxygen up to about 600 mg/L in raw sewage. Water is fully saturated with oxygen at about 10 mg/L, so you can see that you would need to continually add oxygen for nitrification to occur. Sewage works do this via the <"Activated Sludge"> process (below).
- The next is pH, if you have pH below pH7 then the TAN remains ionized as ammonium (NH4+) and relatively non-toxic. You would still have issues with subsequent higher levels of nitrite (NO2-)
- The next is the nature of the biofilm, if you had a filter medium, like <"floating cell media">, or a fluidised bed system, you have more likelihood of maintaining an effective biofilm for nitrification.