Richard Sexton wrote:
Just had an idea. I'll check against my dehumidifier water.


Not relally a good idea, dust, which is mostly skin cells,
gets in there and goes through the nitrogen cycled and becomes
nitrate.

Distilled water from a store is your best bet.


Well, I tried distilled water. Reads 9.3ppm with my Hanna test kit. Now,
I've been reading about NO3 test kits giving false positives for RO/DI
water. I dumped in some household salt into the DI water to be tested.
The same DI water plus salt gives 0ppm of NO3, and 9.3ppm without salt.
Interesing. My cheap Salifert doesn't seem to have this problem.

Nikki