Re: Aquatic Plants Digest V1 #394

Paul Krombholz says...

>When I was growing aquatic plants in algae-free culture back around
>1966-68, I noticed that I had a precipitate in flasks of nutrient solution
>plus iron EDTA that had been exposed to light, but no precipitate in
>identical flasks kept in the dark.  However, enough iron stayed in solution
>to grow the plants satisfactorily.
>Currently, I am using iron DPTA, (diethylenetriaminepentaacetic acid),
>which appears to stay in solution a lot longer.  CIBA-Geigy, agricultural
>chemicals division,  makes it, but it is hard to find in your average
>garden store.

The trace element mixture that many of us are using up here beyond
the tree line contains 42% EDTA and 13% DTPA. It is available  in
some gardening centers. I "believe" that this combination is almost
as stable as  DTPA alone based upon the same reference given in my
previous post.

Dave Whittaker                       ac554 at FreeNet_Carleton.CA
Gloucester, Ontario                  dwhitt at magmacom_com