Re: Just an Idea (plenum)

Karen wrote:
> Charley,
> > *  We can fully remove any anaerobic activity from the substrate.  At the
> >    first sign of anaerobic activity, simply open the valve and the plenum
> >    is "injected" with oxygen.
> My understanding is that we don't _want_ to remove all anaerobic activity 
> from the substrate... that we _want_ a low O2 environment to allow for 
> cation exchange of trace elements.

Ok--I can live with that.  We don't want to oxidize all our Fe+ before
it is caught on an OH- site, for later exchange on a root hair.  :-)

How about having it as a safety mechanism, though?  While vermiculite and
2 mm sand may not have a high risk of anaerobic activity, some of the
substrates tried by people on this list seem to have that high risk.  At
the first sign of trouble, the anaerobic activity can be stopped IMMEDIATELY
without a tear-down (in fact, without any disturbance whatsoever).

I would merely leave that valve closed, and the system would cycle by itself
99% of the time (in the absence of new O2).  The other 1% is when I dose 
nutrients to the substrate, and I think it would be pretty simple to minimize 
O2 addition (only add a couple milliliters of nutrients, no air).

I sure hopes somebody stops me soon.  I'm thinking about trying this on a
big setup!

charleyb at gr_hp.com	or	charley at agrostis_nrel.colostate.edu