>One point about using citric acid to precipitate salts. I think the stuff
>you see coming out of solution may be the organics and perhaps some
>phosphates. It would seem to me that most of the harmful salts would
>actually increase in solubility when the water is acidified. Can any of
>the chemists out there comment on this?
Exactly so. However, I don't think that the citrate salts will build up in
the medium the way carbonate salts will. Also, you may leach the carbonates
from the medium.
Carl Gustafson
Former chemist