10-27-2020, 09:00 AM
Join Date: Sep 2014
| | Re: Plants and Ammonium
Two days ago (25/10/20), I added NH4Cl to raise TAN to 1.5 ppm as measured by the JBL 'NH4' test kit. Yesterday (26/10/20), TAN measured 0.4ppm, NO2 measured 1 ppm and NO3 measured between 5 and 15 ppm. Water pH is around 7.3.
I have calculated NH4-N (TAN), NO2-N and NO3-N at the outset and at the end of this exercise. These three parameters total approx. 1.4 ppm in both cases. So, the plants don't appear to have taken up any of the ammonium. Instead, the ammonium appears to have been oxidized to nitrite and nitrate. I conclude that nitrifying bacteria may have effected this oxidation. This is despite my best attempts to eliminate nitrifying bacteria in this tank. As the tank was scrupulously cleaned with KMnO4 solution beforehand (including dipping the plants and the wood to which they are attached) plus the use of UV-C sterilization of the water column, this is not what I had expected. The tank is also illuminated during the day and light is known to inhibit the growth of nitrifying bacteria. There is no substrate.
I need to take a break right now to give my grey matter a rest.
Hope to be back later today. In the meantime, if anyone spots any errors in my reasoning, please let me know.