I jam packed my refugium with all types of macro algae small, medium, large fern. The thin hairy type fern also. grape, brown ones etc etc. But they can't seems to push the PO4 below 0.5ppm. I running 2x36W PL in the 1ftx1ft refugium. Maybe I need a larger refugium.
Very happy with the performance of the Rowaphos. Didn't even turn my water brown cos the filter capture all of it as it turn dark brown so I leave it there until the PO4 starts to increase again.
Now considering getting carbon to help on the nitrate while my DSB matures.