[APD] Re: The why of the Barr method

["Jeff Ludwig" <jeff at rockytop_net>]

I'm going to pick apart a few comments so far, I'm challenging views to
provoke discussion, not to be a jerk, so sorry if my comments seem a little
rough, it'll be good for all of us in the end... :)

Tony Eales:
> I think you're too quick to rule out allopathy. I agree that the idea
> that plants are pumping allopathic chemicals into the water column or
> substrate is probably incorrect however at the cell surface where
> algae are trying to attach things may quite different. I think it is

Okay, so within the Barr framework, what do I do about attached algae?  Do
these melt away also?  What about BBA in the substrate/on driftwood (this is
a huge problem among even the most seasoned growers)?  Why can't we isolate
this chemical, bottle it and make millions?  The market for a chemical like
this is enormous (almost all of it outside of the aquarium industry).  Same
comments apply to Jim's reply, if these chemicals existed they would be
commercially available already and this would not be an academic pursuit. :)

Daniel Larsson
> It also explains why the Walstad method works over the long term. The
> plants aren't producing the allelopathic compounds nearly as fast,
> but they have much more time to accumulate because of the lack of
> water changes.

Maybe.  Walstad method is based on the sequestering of nutrients in the
substrate, allelopathy is a part of her story but the bulk of it involves
getting nutrients to where the algae can't be: in the substrate as well as
floating plants to take advantage of atmospheric CO2.  These chemicals have
not been isolated yet, I don't believe they play any role in our tanks... I
am not incorrect in saying evidence for allelopathy is shaky at best, Tom
himself doesn't believe they play a role if I recall correctly.

Daniel Larsson:
> Perhaps if you seek the archives for "RUBISCO" thing's will
> clear up. Or the opposite.
>
> I think it's about oxygen-CO2-levels.

Then please explain to me why hooking a bottle of O2 up to the tank, dosing
H2O2 to the water column, running an ozone machine, or any number of methods
I can use to supersaturate the water with these chemicals fails?  Not one
person has ever answered this question for me (with a reasonable scientific
explanation).

Good posts,
Jeff Ludwig
Elkton, MD

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