Re: [APD] Water soluble micros needs low pH?

["Daniel Larsson" <defdac at hotmail_com>]

S.Hieber wrote:
>Are you keeping the aquarium at a pH of 4 or are you only 
>concerned about solution in storage for a prolonged period?

I'm only concerned about the possibility that the EDTA or 
DTPA powder binds with other stuff if the pH is above 4-5 in
the water that is about to be a micronuntrient solution,
instead of the iron, zink, copper etc.

For example:
"Determination of Calcium-Magnesium by EDTA Titration"
http://www2.sjsu.edu/faculty/chem55/55mgca.htm

"all reactions between metal ions and EDTA are pH dependent
, and for divalent ions, solutions must be kept basic (and
 buffered) for the reaction to go to completion"

So if you lower the pH in the the EDTA will not react with
Ca, but (hopefully?) better with Iron with the formation
constants in mind?

Reading the archives with the discussion with Greg Morin 
about EDTA/gluconate I think I'm a bit out of my league 
here 8)
http://www.thekrib.com/Plants/Fertilizer/gluconate.html#7


best regards
Daniel Larsson






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