At our recent orchid festival in Pittsburgh, the topic of removing salt
(NaCl) from coconut husk chips (CHC) was discussed. Most people soak and
rinse the material with regular water or RO/rain water at least 3 or 4
times and check the conductivity of the rinse. However, there apparently
is a study out the indicates that this is not enough for removing all the
salt and that salt can continue to slowly leach out over time and cause
problems (particularly when the medium is allowed to dry and is then
rewet). I do not have the study or the names of the people who did it, but
their results supposedly indicated that the CHC must first be soaked in a
large excess of calcium nitrate ( 1 cup for a 5-10 gal soak tank), then
rinsed and then soaked again with a lesser quantity of magnesium
sulfate(Epsom salt, half cup same tank size) followed by rinsing. The
study apparently analyzed the medium and the sodium uptake of plants by
tissue analysis. Anyone know more about this? I personally have had some
trouble growing phrags in a coconut husk medium (charcoal etc added) with
standard washings.

Thanks

Charles VanDyke