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Re: Trace element supplementation/fertilisation

> From: Tom.Wood at ci_austin.tx.us
> Subject: Re: Trace element supplementation/fertilization
> I'll try to stir up an argument.


> > James Purchase wrote:
> > 
> > >"PMDD can work very well - IF you know what you are doing. If you DON'T
> > know
> > >what you are doing, it is better to stick with commercial preparations
> > which
> > >are designed for aquariums."

	They may be _intended_ for aquaria, but I suspect that quite a few
weren't _designed_ at all, apart from "buy low, sell high" as far as price
is concerned.
	That should stir things up a bit.  :)

> > Tom Wood wrote:
> > 
> > >The trouble is, commercial preparations that don't disclose ingredients
> > >leave you in a state of perpetually never knowing what you are doing,
> > >whether you think you do or not.


> > >Plant fertilizer is really simple stuff once you know what is in each
> > >component of a fertilizer regime and why it is there.  

	Measuring _all_ the components is a problem, though.

> > Karen Randall wrote:
> > 
> > "The thing that amuses me about this sort of statement is that I have yet
> > to
> > hear of any of the PMDD advocates actually formulating their own trace
> > element mix.

	Go back and read the article Kevin and I wrote at the start of
the "PMDD" idea.  I began with my own mix.  I use commercial stuff now,
because it is a lot less trouble and I don't have time to do a lot of
(any?) experimenting.  If you look at information on the amounts of trace
elements in plant materials in plants, that will tell you roughly the
proportions to use.  There is quite a bit of room for error.

> > to think
> > that you are doing things "more scientifically" by mixing your own
> > hydroponic trace element mix with distilled water is only fooling
> > yourself.

	It would be if one carried out some experiments with well
controlled conditions and varied the composition of the mix.

> >  Now if you're doing it because you want to save money, or because you
> > can't find a well balanced commercial trace element supplement in your
> > area, those are legitimate reasons.  But if you're using _anybody's_
> > "trace
> > element mix" and you think you are "fine tuning" in any way that you
> > couldn't with a commercial product, your just fooling yourself."

	Of course, using a commercial trace element mix with KNO3,
K2SO4, MgSO4 is probably a factor of 50 or so less expensive than
buying products manufactured for aquarium use.  Getting the trace
elements separately isn't likely to be much cheaper than that.

> > I just want to know what I am putting
> > in my tank, and why.

	There have been appeals for help on this list where it became
evident that the basic problem was that the owner of an aquarium was
in trouble _because_ (s)he had depended on unknown commercial substances
to fulfil basic requirements (e.g., pH control).  I have no problem with
using commercial stuff _if_ the ingredients are stated.  Otherwise,
forget it.

>  Although I do have to trust that Paul knew what he
> > was doing when he and Kevin chose the Plantex CSM trace element mix,

	"If we knew what we were doing, it wouldn't be research." ;)

> I
> > doubt it really matters all that much.  The amount needed is "some", with
> > iron acting as a proxy for measuring. 


> > But more important, the very exercise of working
> > through the PMDD regime yields a great deal of understanding as to why
> > each component (both micro and macro-nutrient) is included.

	i.e., observe, think and learn, instead of buying magic potions
to fix everything without thinking.

> > This doesn't have to be all that complicated. 


> > Tom

	Thanks, Tom.

Paul Sears        Ottawa, Canada