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Re: Aquatic Plants Digest V2 #580

>From: freshwaterff at earthlink_net
>Date: Sat, 15 Mar 1997 06:32:23 -0800
>Subject: Tetrasodium..........
>...............I have a small bottle of Tetrasodium
>ethylenediaminetetraacetate.  I know that this is used in the chelation
>of minerals.  My question is, how is it used?........

It is called EDTA for short, and it is a chelator, used primarily to hold
iron in solution.  Actually, EDTA is not a very good chelator for aquarium
use because it is broken down by light over a period of a week or two and
loses its ability to keep iron in solution.  There are better chelators
available.  See the post on March 1 from Sparrow for an analysis of
Sequestrene, which looks like a very good iron source.  See, also, the
comments on Mar. 2 by David Whittaker.  I use Diethylenetriaminepentaacetic
acid (DTPA, I think) as an iron chelator, and it works very well for me,
keeping iron in solution for at least three months.  I dissolve the DTPA at
0.1 moles per liter and ferrous sulfate at the same molar concentration
together in water to make a concentration of 0.01 molar iron DTPA and heat
to boiling.  With a few drops of conc. HCl to inhibit mold growth, the
solution keeps indefinitely.  I add it at about 1 CC per gallon of aquarium

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In Jackson, Mississippi, cooling down after warm spring rains.