Nh4+ Vs No3-


New Member
Jan 4, 2019
Hello, just thinking about mixing my own NKP.
I want to try to add some NH4NO3 along with KNO3, but wanted to know how should I calculate the real equivalence of NH4 to NO3. I use to make NPK without NH4 and usually had a dose, let's say single spray, adding 0.5ppm of NO3 to my aquarium. N in NO3 is only 23%, so that means I actually add ~0.12ppm of N.

In case of adding NH
4, N is about 78%

Based on
barr report analysis of ADA Brighty Special Lights (sorry no links are allowed for me yet but could be found googling "ada green brighty composition") N coming with NO3 ~1003.4 ppm (average NO3 readings 4362.5ppm x 23%) and N coming with NH4 ~671 ppm (average readings 860 ppm x 78%) so tham means that 40% of all N is coming with NH4.

My questions are: has anyone any experience mixing NPK not only from KNO3 but also with NH4NO3 ?

Is my evaluation of overall N accessible to plants correct and logical?
Aug 3, 2017
Milan, Italy
Quoting BarrReport's article "Nitrogen Cycling in Planted Aquariums":

"NH4+ preference was observed at levels between 2.0 to 0.5ppm and NO3- preference when the NH4+ is less than 0.5ppm. At 0.1ppm NH4+, no NH4+ is removed in the presence of NO3-."

"There is a strong relation of high dissolved oxygen with low NH4+, allowing bacteria to oxidize the NH4+ and compete with the microphytes for this nutrient. Overloading with NH4+ produces a microphyte bloom. Adding high oxygen levels with pure oxygen did not prevent the microphyte green water algae bloom when NH4+ (at 0.5ppm) was dosed (Barr, 2003)."

"Having some fish waste or other sources of low level NH4, but not enough to stop NO3 uptake seems to be the best approach."
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