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On Thu, 29 Jun 2000, David Youngker wrote:
> Just as usable as potassium nitrate, but not as handy - the anion is
> chloride, which will basically raise the conductivity of the water while
> increasing the osmotic differential. At least with nitrate you get a useful
> secondary ion.
Nitrate is more useful than chloride, but both raise the conductivity of
> If you're using it as a potassium supplement for plants, there's this to
> consider: if the cation is being consumed, what's happening to the remaining
> portion? And what's being done to restore the ionic balance of the water?
When a plant imports a charged ion (nitrate is negatively charged) it
either exports an equal amount of charged ions simultaneously or imports
ions of the opposite charge at the same time. I don't think there is a
large or long-term ionic imbalance built up in the tank, except the small
one that at least some plants maintain near their roots by actively
pumping positively charged ions (hydrogen, mostly) out.
If you want to add potassium without adding nitrogen then your main
options are potassium chloride, potassium sulfate and potassium
bicarbonate. The bicarbonate adds alkalinity, so if you don't want that it
narrows choices to either the chloride or the sulfate. If you're already
adding sulfates for something (epson salt for magnesium, for instance)
then it might be reasonable to use potassium chloride to keep the
composition balanced. If your water supply contains a particularly high
concentration of chloride, but a relatively low concentration of sulfate
then you might want to use the sulfate.