Purigen removes proteins, nitrites and nitrates, ammonia, and a broad spectrum of organics, yet its impact on trace elements is minimal. It significantly raises redox. It polishes water to unparalleled clarity.
So if I understand this right you could potentially use this stuff for all of your biological filtration needs and not have a protein skimmer at all?
The only thing you would need would be a mechanical filter for the big junk? What is redox?