Low Nitrates

[cbjfan75]

Have a planted, well stocked 55 gal aquarium that has been going for a few months now. The current light is a 36" Marineland that I am wanting to replace soon as it's not lighting up enough of the tank. I did my weekly test this morning prior to a water change and came up with 0 on the Nitrates. Is this a normal occurrence? I know it's not the test kit as I registered nitrate in another tank a few minutes prior.
Suggestions?

 

[Delapool]

Are you dosing any ferts? Good check of the test kit.


Mine is every so often getting 0 to 5ppm and I'm increasing my ferts a tad to compensate. A fine line as I don't want it over 40ppm. This is a CO2-injected tank, about half grown out and fully stocked.