I'm not real sure, but I suspect the problem was more to do with the amount of soil and the soil/cap ratio.
I've done two tanks with MGOCPM, and never really had an issue, the deepest was about ~2" of MGOCPM and ~2" flourite cap. From what I read on here, I think it's pretty rare that someone uses more then 2" of dirt.
Second tank uses about ~1" of MGOCPM, and about ~2" flourite sand cap.
I didn't do anything to the MGOCPM, just put a scattering of dolomite on the bottom, and then the MGOCPM straight out of the bag (sifted for the second tank).
I don't think the clay will actually add much iron, but at the same time, I don't think it will hurt anything either, I just suspect it's unnecessary.
I've done two tanks with MGOCPM, and never really had an issue, the deepest was about ~2" of MGOCPM and ~2" flourite cap. From what I read on here, I think it's pretty rare that someone uses more then 2" of dirt.
Second tank uses about ~1" of MGOCPM, and about ~2" flourite sand cap.
I didn't do anything to the MGOCPM, just put a scattering of dolomite on the bottom, and then the MGOCPM straight out of the bag (sifted for the second tank).
I don't think the clay will actually add much iron, but at the same time, I don't think it will hurt anything either, I just suspect it's unnecessary.