On Wed, 18 Jun 2003 17:08:52 -0600, Chuck Gadd wrote:

I did a nitrate test with a Hagen kit and came up with 0mg/L.
I guess it should be somewhere around 10-20mg/L for optimal growth?

Be VERY!!! careful trusting the test kit. Maybe mix up a reference
sample, or repeat the test using a reputable test kit before trusting
it. For "reputable", I'd say either Seachem or Lamotte. Not sure
about the Hagen nitrate kit. If the test kit isn't properly
indicating the nitrate level, then it's easy to massively overdose
without knowing it.

Well, anxious to try some of this chemistry, I found a pound of Green
Light Stump Remover at the local Lowes. It claims to be KNO3.

It mixed up clear, and has no funny colors, odors, etc., so I decided
to try it. Now to test the test kit...

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.

FWIW,
Greg