[APD] RE:Black Turface

["Thomas Barr" <tcbiii at earthlink_net>]

Bill, 
Black Turface looks pretty good, you can m ix with whatever type of black
sand you want or use nothing but Turface. Many folks do except most use the
red colored Turface.

At 8-12$ a 50lb bag, seems pretty cheap and it's rich in iron.
See the link. Call 1-800-207-6475 for availability in your area etc. 

John, I added 10mls 3-4x a week in a 20 gal with 110w(Flourish CMS and
TMG), I really did not see a dramatic improvement in growth vs 5mls even
with sensitive plants(Nesaea, Amaninnia, Crypts, Red Cabomba, Eustralis
etc). I suppose the more concentrated humics may be releasing the Fe
but......................relative to the plant itself, reducing Fe3+ to
Fe2+ is not a big issue energetically speaking and the redox does not have
to drop that far for this to occur in the substrate.

The plant does not need that much Fe anyway.
It's only one electron from Fe3+ to Fe2+.

Compare that to NO3 vs NH4+ reduction, the plant needs far more nitrogen
that it will ever FE, and it's a whopping 8 electrons to reduce the
nitrogen to a usable form vs the iron. But there are other things in the
traces.......so, while one may not make a huge difference, perhaps several
can(the synergistic effect), but it'd still take a lot more traces to equal
the Nitrogen and see a visible effect over say a three week period. 

Adding NO3 to the substrate is a two/three edged sword. It can be
denitrified and lost to plant uptake, and buffer the redox(along with
iron), it can be reduced easier in the more reductive substrate perhaps
making NH4 more available. I kind of think that bacterial mediated or
inorganic reduction of NO3=> NH4 will not occur, this requires a lot of
energy and provides a very low yeild. Maybe tiny amounts of NH4 are
liberated, but tiny amounts will not yield dramatic growth differences
either.

So, NO3 for the roots might be all we got for now. Some NH4 binding but I
think since that NH4 is at such low levels, and there are plants, bacteria
and algae all comopeting for this cation, it's unlikely much will ever get
bound to the grains/surfaces.

We also don't know how well this stuff absorbs/desorbs but that can be
figured out. That's part of my reason to add Nitrogen forms to the
substrate and the soaking idea but it may tell us why it works well in the
long term and how much and at what rate nitrogen/PO4 may act.

I'll report back when I know more.

And for folks wondering about adding low grade coal based stuff, activated
carbon is what precisely?
This is one reason why I'm hoping it'll hold the NO3/PO4. I may try soaked
carbon as well, not that much different than lignite(and it sure seems to
soak up humic acids quite well also now doesn't it?).


Regards, 
Tom Barr




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