Every living organism needs building blocks to create new organic tissue. They also will slow down and then stop cellular activity at a high enough level. The level at which each organism or cell will be affected is different and can vary widely from thing to thing. You can google toxicity levels of high nitrate for different things... plants, fish, etc.
This is a bad false equivalency, but your body needs some sugar for brain function and other things, but slightly too much will slowly destroy your body and way too much can cause damage much quicker and at some level, you will die. ... some alcohol and you can have a good time... too much and you can die. Macro algae needs some N and P to grow. Too much and it will stop. Even more and it will die too.
The dinos are poisoned and/or slowed by the higher levels of N - toxic at pretty low levels compared to other things in our tanks. There is a long thread on here that says with the post in #22 has said, but they are not correct. The premise and assumptions are wrong, but the result works if you raise the N. N nor P are not a food source or fuel. They are building blocks for organic tissue. The dinos and/or other microfauna need only a trace to survive and most of what it in the tank is not testable and they had enough before people dosed the nitrate -the microfauna that the thread supposed will grow faster with more nitrate are most likely growing fast enough already. The nitrate dosing is toxic to the dinos and they die back.
