I've switched gears and I'm going to a South American Cichlid tank and I will need the K and Mg. I know front loading (weekly dosing after a water change) for some components is not advised. How about K2SO4 and MgSO4?
I keep African and CA/SA cichlid in my planted tanks and front load all nutrients after weekly 75% water change with the exception of Fe, Ca and Mg. I dose chelated DTPA and Gluconate iron every other day due to bio unavailability of Fe3 in aerobic environment. I never see the need to dose Mg and Ca though as I have dolomite substrate and limestone rock that are reservoir for both minerals, besides my tap water has enough hardness.
Just wonder what form of Fe is in Dennis Wong APT complete as Fe/PO4 combo can potentially precipitate each other out.