Re: Jim Kelly's vermiculite recipe

> From BobWurster at aol_com Thu Jun  8 01:23:06 1995
> > Steve said:
> > > I plant to use vermiculite, mud, gravel & sand on a RUG (no heating
> > > coils) set up on a 75 gal tall tank for Aponogeton propagation. 
> > > Expect reports on the mailing list: good or bad.
> [snip]
> I am inclined to discourage you from attempting to use this substrate with
> any kind of undergravel filter. The mud/vermiculite mix is too fine to allow
> circulation. If you do get circulation, the mud will blow into the tank. It
> might work if you put the substrate mixture and plants in pots.

Yes, that is a good point. My plan is not to use a powerhead of any sort but
rather only about 1-5 cm of hydrostatic pressure. I hope that will be sufficient
to induce a suitably low flow rate as per the heating coil method. I think I
should be able to alter the hydrostatic pressure by the height of a tube which
receives the outflow from a filter or pump. (drill holes whatever) I will post
this on the list and hope for additional comments. Does anyone have any idea
of how much hydrostatic pressure would be ideal or the ideal velocity of water
being transported through the substrate or a method for measuring this? The
flow rate should be dependent only upon hydrostatic pressure differential, the
thickness of the substrate and it's liquid permeability. Sounds like data we
should be able to discover from soil lab research.

BTW, I should credit David Webb with the concept for this design.

Is everyone still getting the mailing list except me? The last one I got was 108.

- Steve