I've found chaeto to be extremely effective with phosphate and nitrate removal all in its own. So effective that I have, in fact, removed every other type of filtration on my system. Took both then skimmer offline and the phosphate reactor down and chaeto is true workhorse at nutrient removal on my Ecosystem Miracle Mud refugium. Are you using it for nutrient removal primarily, or ph stability at night?
I would say pH stability with the added benefit of some nutrient removal. Also gives a place for the amphipods to do their little thing.