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Re: agro vs. lab grade

> Date: Mon, 10 Nov 1997 21:03:19 +0800
> From: "Jonathan Uy" <5js at durian_usc.edu.ph>
> In the practical PMDD information in the Krib there were two grades of KNO3
> and K2SO4 mentioned.  The agro grade and the lab grade.  I like to know
> what most of the hobbyist are using in mixing their PMDD.  Is there a
> difference in concentration of lab grade to agro grade?  There is a huge
> price difference and I wonder if it would make any difference to the
> concentration levels in the aquarium?  Feedbacks from people who of have
> use both grades are most welcome.  

My guess would be that lab grade would be 99.99 to 99.9999% pure, while
the agro grade would be maybe 95-99% pure.  The extra stuff in an impure
grade may well include trace elements and other harmless or useful stuff.
Agro grade may be harder to dissolve.  I would go with the cheap stuff
and measure it as if it were 100% pure.  After all, most of the other
things we put in an aquarium are far from chemically defined, and PMDD
is something you adjust to match your needs.