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RE: Hydroponic Plant Food

Tom Wood seems to take exception to parts of a recent posting I made. I had
written the following:

"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."

Tom responded with:

>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.

Yes, Tom - I agree with you 5,000% on this. I wish more companies would
disclose the contents and the composition of their products. As hobbyists, I
guess that individually we can continue to lobby the industry for more

Failing that, I wish that a body like the Aquatic Gardener's Association
would submit samples of the major lines of aquatic plant fertilizers to
independant analysis so that we would at least know what elements are there
and which ones are missing or in short supply. I've floated this idea before
but it has always been shot down (hasn't it Steve...). For anybody familiar
with the online magazine Aquarium Frontiers, they have done such tests
recently on the major brands of marine salt mixes. I don't see anyone suing
them. Perhaps this is an issue that the AGA should seriously consider (or
re-consider, as the case may be).

As to my recommending that the earlier poster stick with commercial
preparations unless he knows what he was doing, I plead guilty and stick by
my recommendation. He was asking if a fertilizer which contained substantial
amounts of several macronutrients would be suitable as the micronutrient
component of a PMDD style mix. I mean no disrespect here, but he obviously
doesn't know what he is doing - and he could end up doing more harm than
good to his tank. That's why I also recommended that he review some of the
material available online, and that's why I gave him several URL's to visit.

>At the time I didn't know any
>more about what I was doing than what I gleaned from the Sears-Conlin

Again, the Sears-Conlin paper, while valuable, does have it's limits. Some
of the "target" doseages for certain nutrients seem to me to have been
chosen out of a hat - I know for a fact that in some of my tanks a 0.1 ppm
level of Fe would lead quickly to an algae bloom. I'm not saying that the
paper is wrong, it's just not written in stone. Don't give it the veneration
some people reserve for Scripture.

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

You think so, eh? Good luck. I've been at this for over 30 years and I'm
still a beginner.

James Purchase