surprisingly low nitrate reading - what does it mean?

[RoseFishWatcher]

Last week, I decided to be lazy and not do my scheduled water change unless nitrate was high. I tested all of my tanks (6 FW, 1 SW). All 6 FW tanks tested at 0 nitrate (they have been set up over a year and no major changes). In the past (I don't check regularly) the readings have been 5 on my planted or understocked tanks, and 20 or more on my snail tank (snails are pretty messy for a 6 gallon, lol).

Concerned that my kit was bad, I took a sample of snail water to the LFS, since that was most likely to be high in nitrates. After the lady gave me some trouble (she tried to insist that nitrates didn't matter at all in FW, only in SW) she confirmed that 0 was correct. (I decided to just do the water changes anyway - just because I've convinced myself that's the best care I can give).

I just don't understand WHY that is right. Admittedly, there are fewer snails now than when I was getting higher readings, but I would still expect more than zero. The tank has no plants, nor any nitrate export other than water changes (as far as I know... )

Any idea on why all my tanks have zero nitrates? I understand the basics of cycling quite well, and I'm certain there isn't a problem with recycling. Could there be some process taking place that completes the nitrogen cycle, resulting in N2 gas? I certainly haven't seen anything that suggests this is taking place, and don't have any anaerobic areas that I'm aware of.

 

[Cathy G]

How old is your tank, how big and what fish are in it?
Cathy

 

[Cory Keeper]

plants is about the only way to reduce nitrates to zero, unless you have anaerobic spots (and lots of them) in your tank, which you've stated you don't have. I'm not sure what to tell you then.

 

[Coler]

what kind of test kit ? is it in date ?

if its the API are you doing the 30 second shake on bottle two and one minute on the solution when mixed ?

0 nitrates is not really going to happen in anything other than a lightly stocked heavily planted tank - as you note, some process has to be occurring to remove nitrates.

 

[Squawkbert]

If you use Prime and an API kit, you can get low NO3 readings.

There are worse problems to have... I dose macros daily and can't get much of a reading from my API kit, because I use Prime and because I'm pretty heavily planted.

 

[Mgamer20o0]

so all the tanks that came back with 0 were planted tanks? plants do use up a lot of nitrate so that could be your answer right there.