Now I'm gonna do the speed version of this question, but feel free to answer at whatever length be appropriate!! Natural PO4, that which arises from fish feeding, waste, natural decay etc is this a different form of PO4 than the dry salt I use? Or is it that one favours algae growth more than plant growth or is easier for plants to assimilate? I understand that the PO4 I add is very much a friend and the other is not I'm just curious as to why? Cheers :?