Re: PO4 and Fe

[Thomas Barr <tcbiii at earthlink_net>]

> I have never seen dramatic metabolic response when adding KH2PO4, but
> the pearling is almost always very good (I guess that's what you mean by
> timing the metabolic response - ie timing when intense pearling occours?).

Yes. If you have sources like tap water etc to prevent PO4 limitation etc,
you will not see this. But if you limit the tank, note the algae etc, and
plants, adding everything but POO4, then add it, you'll see a rapid response
and uptake. 

> So I guess I have enough phosphate from fishes/wastes right now.

Maybe. Might be something else(CO2, not enough of something etc).

> But when I keep up on everything (except KH2PO4) and if/when the
> pearling in the future stops I will test the response of adding KH2PO4.

That's a practical experience that should do well.
  
> (OT)
> The only time I have seen dramatic pearling response is when I have
> pipetted some 3% H2O2 over Glossistigma next to the glass generating
> extreme pearling (mostly from the roots). In a couple of seconds
> the Glosso roots pumps out oxygen like crazy.

That's chemical torture, not uptake P metabolism:)

Here's a common sense question.
A question you might ask is this about PO4:

Why not add Fe to precipitate out excess PO4 that supposedly plagued every
ones tanks causing algae? I mean if the PO4 precipitates out fast/easy etc,
then adding the Fe etc should remove it?
Why would you try to limit two or more nutrients carefully?
You only need one to affect things this way.
How is it that folks with very high PO4 levels ,maintain these levels for so
long while adding trace elements/iron? Why don't their PO4 ever go down
significantly? Probably because it is not significant.

On a practical experience level, it just does not seem worth worrying about,
the Fe does not seem to remove much PO4 over the time and concentration and
pH levels in the tank.

Regards, 
Tom Barr