The algae and plants that are put in a refugium and remove nitrates, phosphates, some heavy metals, toxins, and co2
from the water. For a beginner to the hobby, I think that will DEFINITELY suffice. My 40g will never see a protein skimmer since the coral I will be putting, greatly benefit from dissolved organics in the water. My 75g will probably see a hob
protein skimmer since i do not have room for a refugium. I feel like this argument is the same as metal halides vs t5ho. Everyone has their opinions, and there are pros and cons to each.