On Thu, 19 Jun 2003 00:57:30 -0400, Greg
wrote:

As per Chuck's suggestion, I mixed 1 tsp. with 500ml of water. Then
mixed 2 ml of that solution with 1 liter of water. According to the
Hagen test kit, the resulting mixture has a nitrate concentration of
about 3 mg/L.

Tried the test again with a Tetra kit. Although the kit is a few
years old, it came up with about the same reading.

If I recall correctly, mg/L and ppm are interchangeable?

So, either the stump remover contains filler, or the test kits are not
accurate.

I think the stump remover is close enough to call it pure KNO3.

And yes, mg/l and ppm are the same.

Some nitrate test kits report the results of nitrate-nitrogen.
For those kits, they report only the nitrogen portion of the nitrate.
To get to ppm Nitrate, you need to multiply the value by 4.4, which
would give you 13.2, pretty close to what you should get for the
reference solution.

So the kits might be accurate after all, if they are reporting
nitrate-nitrogen.

But, keep in mind that if your desired level of nitrate is 5ppm, that
would be 1.13ppm Nitrate-Nitrogen. Does the test kit go down to that
level? What is the lowest measurement value for the kit?


Chuck Gadd
http://www.csd.net/~cgadd/aqua