Re: EDTA photodegredation

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.

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174

Where students and faculty are suffering from spring fever!