Is iron chelated by EDDHA ok for use in the aquarium? I got some at a garden shop today about 4 for 250g @ 2% Fe, 2% MgO, and 3% Mn. I am not sure whether to put it in the substrate or to dissolve it and pour it in. Your thoughts please? <<<<<<<<<<<<<<<<<<Spug (Sparrow) London, UK.>>>>>>>>>>>>>>>>>>>>