Nitrate / bad kit or plants just consume that much?

[AK-71]

Here is the situation
One thing puzzles me - in my planted tank nitrate level doesn't go above 5ppm level. I have monitored my old tank cycling through normal ammonia / nitrite phases in ~3 weeks (didn't measure nitrate than, as test kit suppose to give false levels due to nitite present in the water).  
Couple weeks after the cycling ended and ever since my nitrate levels are bellow 5ppm (first color on the scale). Moved everything into a new tank more than a month ago - tank went through a mini-cycle and still not much nitate after. I am actually starting to add Flourish "nitogen" as a fert. now and plants seem to respond  :?
I vacuum clean the gravel when changing water.
Fishload in 55 gal planted tank:
6   glowlight tetras
10 cardinals
1 gold ram
2 cory cats
4 ottos
3 pearl gourami
Added 2 more cory catfishes yesterday

Question:
With this fishload I think I should be close to overstocking - WHERE all my nitrogen goes?
a) Is it all consumed by plants?
b) Or I just have a bad kit?   (it seems to react to Flourish Nitrogen about right according to what they say on the bottle though)
c) May it get "bound" by something else in Flourish line I use?

How common is it to have such a low nitrate levels in yous experience?

[Mzungu]

Re: Nitrate / bad kit or plants just consume that much?

I would say it's pretty common. Most of my tanks (all planted) have little to no nitrate! Plants that are growing well really do use up a lot of it.  :)

[armthehomeless]

Re: Nitrate / bad kit or plants just consume that much?

My planted tanks have no nitrate. I think it pretty common...

[AK-71]

Re: Nitrate / bad kit or plants just consume that much?

Thank you, I feel much better now :)
Another good reason to have plants then :)
Besides the "beaaaauty" factor

[Mzungu]

Re: Nitrate / bad kit or plants just consume that much?

Thank you, I feel much better now :)
Another good reason to have plants then :)
Besides the "beaaaauty" factor

Exactly!  :)