how high can it be?? 30ppm 40ppm 50ppm?? Urea will no longer remain Urea in the water, it will convert into nitrate within hours, soon as you add it to the tank, plants goes for right away. any urea left behind convert into nitrate, second source of nitrogen for plants. EI people knows how high you can go with the nitrates without any problems, they do it all the time.
Didn't think of that. But this basically double the brown line(~60ppm peak). But that is for tanks that doesn't need to be dosed.
I think this theoretical peak
for normal EI is 45ppm. So 60ppm maybe isn't that high?