The nitrate levels will only go up if in the inputs exceed the outputs. In a plant-less tank there are no outputs for nitrate other than water changes, so the levels go up as nitrite converts to nitrate. 1ppm of nitrite will make about 1ppm of nitrate. The nitrate climbs into the 40s and 80s because it slowly accumulates. Planted tanks are different. Now you have an extra nitrate input (fertilizers) and an extra nitrate output (plants). The quantities you are adding as ferts and the quantities plants are using can dwarf the amounts coming from the cycle on a lightly stocked tank. So, long story short, I wouldn't be surprised if you dont see the climb in nitrate described in the articles on cycling your tank.
The other thing to keep in mind i the large uncertainty values associated with these API tests. At least in my hands, reasonable people could be off by one color bar in either direction. That makes for 100% error at some values. It may take some time before there is enough of a bump to be sure it is accumulating.
Nitrate Inputs: oxidation of nitrite from BB, small levels from top-off water
Nitrate Outputs: water changes, chemical filtration (if present)
Nitrate Inputs: oxidation of nitrite from BB, small levels from top-off water, macro fertilizers
Nitrate Outputs: water changes, chemical filtration (if present), fixation by plants (only really removed on trimming)
For the chemically inclined. Do you know if the ppm values on API kits are ammonia as nitrogen (NH3-N) etc or the straight ppm values?
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.