[APD] RE: substrate vs the water column

["Thomas Barr" <tcbiii at earthlink_net>]

> >I just found several more references. These precisely and directly
support
> >my contentions about water column being the source of nutrients when
> >adequate contention is present there.

> I don't doubt that, but aren't roots more efficient that leaves at doing
this?

At transporting nutrients to the leaves?
Errr.........I really do not see how. There is no evapo-transpirational
pull in submersed aquatic plants either.

> That's all roots do and there's typically as much of them as there are
leaves.

So that assumes what? A root tank?
That is not all roots do, try Spadderdock, lilies, Hydrilla, Potamogeton,
Swords, Crypts, => roots are storage organs as are leaves, they also
provide mechanical support to  keep the lotic weeds like Swords attached in
fast flowing water that shears the banks where they live.  

> Roots can sit in such nutrient rich muck it would turn a tank green
overnight
> if there was that much fertilizer in the water column.

Well at 2ppm of PO4, 30ppm NO3, that is pretty mucky. No green.
I dosed a month's worth of Flourish the other day to see what might happen.

> I'm being rather crypt-centric what I say this. I'm sure it doesn't matter
> for, say, Egeria najas...

No, I say it doesn't matter for Crypts and swords, I've somehow grown them
well in nutrient poor media for years. Swords are monstrous weeds.
How do I manage that if that is the case? Humbug. The observations I've
seen don't suggest they care if there's enough in the water column anymore
than Egeria najas. 
I've had both for many years in RFUG's together(extremely nutrient poor
media). 

> But, why do we care? Either work, both, IMO work better than either. YMMV.

Perhaps "the how" is all you pursue then rather than why? 
The need for better understanding of the __individual components__ is great
when suggesting adding "both" together. What role does each component play
and why?
When someone says, Crypts or swords prefer this or that, do we really know
they "prefer it" anymore than any other plant? 

Regards, 
Tom Barr

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