Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
As jason says: Use Epsom salt for magnesium, but also include a calcium source.
I also get pool chemicals for some aquarium uses.
I tried the stump remover KNO3 and it does not dissolve very well, and leaves remnants in whatever containers I use to mix it.
I have Osmocote in most tanks, but I also use the dry ferts which are really agricultural grades of KNO3, KH2PO4 and K2SO4.
I am looking for some reasonable source of trace minerals. Currently using CSM+B. Actually, it probably is not too bad a price. I have looked into buying each of the chelated minerals separately, and they are not cheap.