The salt test kit does not measure baking soda levels, so I guess it
measures only the chloride level. Baking soda would be measured by the KH
(Carbonate Hardness) test. The value should be above 80 for all ponds and
above 100 if you are using a bead filter. The bacteria need carbonates to
help digest the ammonia and nitrite, and so it will decrease. The
carbonates also stabilize the pH, preventing wide swings by providing the
buffering capacity. The use of calcium carbonate (limestone), or calcium
magnesium carbonate (dolomitic limestone) will help if the GH (General
Hardness) is also low, but both are somewhat insoluble. Calcium carbonate
is more soluble than calcium magnesium carbonate, so would be the better
choice.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html

"JGW" wrote in message
...
I've been adding a lot of baking soda as a buffer. I've been checking
the salt level in my pond, and it doesn't show any change. I don't
want to kill my plants.

Does anybody know whether most salt test kits test for sodium,
chloride, or both? Is it the sodium in salt that kills plants?

Any reason I can't use powdered magnesium/calcium carbonate to
increase alkalinity as long as my general hardness is also low?