the nitrate levels seem somewhat high (despite it is a plant tank). Personally, I try to keep mine at 5-10 ppm. Any more, I would think you're risking algae growth.
plants don't use up nitrites... and it is toxic to fish (more so than nitrates). I don't know what is the tolerable level, but if it does get too high, just do frequent water changes.
the kH is a good level (kH=4 is "ideal" when injecting CO2).
Do you have a iron test kit? IMO, its one of the most important tests for plant tanks.
Also, if you can test the phosphates, the general rule is to keep it less than 1ppm, but even at 1ppm, it is very easy to have an algae bloom. So I'd aim for .5 ppm or less.
Here's a link to an article that I found very helpful and informative.. kinda lengthy, but well worth the read.
www.cam.org/~tomlins/algae.html
