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I am surprised that Viateur needs help on conducting a Google
search on Virus + Hypochlorite. Although a lifetime of practical
experience as a Biochemist and Experimental Cell Biologist assures me
that hypochlorite, i.e., chlorine bleach, can clean dirty orchid pots, the above
Google Search produces over 500 PAGES of references to the effectiveness of
hypochlorite as a viricide, which should even convince Viateur, e.g.,
Efficacy of Calcium Hypochlorite as a Disinfectant against the Shrimp Virus
Baculovirus penaei, by Leblanc & Overstreet, J. Aquatic Animal Health 3,
141-145 [1991].
Anyone attempting to use the pot
cleaning cocktail advocated by Viateur should be advised that the vinegar
would liberate the chlorine from the hypochlorite in one fell swoop, so you
better have lots of good ventilation or a gas mask. Such a bath
would retain no residual hypochlorite for treating another batch the next
day. The residues on our pots in South Florida are NOT removed by even
strong acid and are probably due to Calcium Silicate since our water is high in
silicate. But it's a principle of Physical
Chemistry, which might seem counterintuitive, that if there were
salts or precipitates within the pots that were difficult to leech out, [how
does one know that as a fact?] they would be equally inaccessible to orchids in
those pots. Viateur seems assured that adding vinegar to the hypochlorite
prevents build up of crusts because he has read the claim in the literature, but
based on my own "life experience" I doubt it, nor can I see any technically
sound reason why it should.
The reason that pots shed residual chlorine
when allowed to dry over night is due in part to atmospheric carbon dioxide, an
acidifying agent, that lowers the pH of residual hypochlorite and converts
it to volatile chlorine gas. Besides, anyone familiar with orchid flasking
techniques should realize that orchids and their seeds are surprisingly
tollerant to chlorine. Also keep in mind that orchids have a high
requirement for calcium; small amounts of calcium retained in the pots leaching
back into the medium would delight the orchids, not poison
them.
Bert
Pressman
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