I don't know if I would experiment with it in the water column but I do know someone that makes dandy substrate fertilizer with it. Go to an arts or crafts store that sell dark clay (you know, something that got iron in it). Pinch off a piece and flatten it to a quarter-size disk (you know, two-bits). Put a pinch of that stuff on it and ball it up again. Push it under you iron-thirst plants and there you go. They will grow like crazy.
Andrew, MASI Treasurer
This message is always under construction: 75-gallon tank; 2, Eheim 2026 filters - one twice broken; Tek Light with 4, 54W T5s (6000K) ; Sand on top of 4:1 sand:clay mixture; Milwaukee CO2 controller; PlantGuild vortex CO2 reactor; pH = 6.6, kH=70mg/l, GH=120mg/l; EI; Flourish excel on 50% weekly water change: AGA Member.