Fwiw, chaeto and gha should be consuming similar amount of N and P.
Please keep in mind that NO3 and PO4 consumption isn't some linear sequence where they go into your fuge, gets sucked up by chaeto, then the the return pump pumps up clean water. Whats really happening is that no3 and po4 is being exposed to all organisms in your DT and sump at the same time so is being sucked up by everything at the same time as long as there's light to photosynthesize. Then this becomes a math game of relative surface area exposure, critical biomass of the chaeto vs nuisance algae, and the light conditions of DT vs Fuge. So, what end up happening is that just bc chaeto is growing in fuge doesn't mean gha can't grow elsewhere. The goal of the Fuge is to keep the competition in favor of the chaeto so that growth of nuisance else elsewhere is slowed, but never elinimated. Then its up to your CUC to keep it under control.