A big benefit of natural algal filtration is that it grow pods, naturally. So not only does the algae absorb ammonia, nitrite, nitrate, phosphate, CO2 and metals, but copepods and amphipods get lots of natural food (that's what they eat - algae) so they multiply a lot. And they are protected inside the scrubber, until they fall out of the holes. And, the amphipods get to eat the copepods too. Bristleworms and fireworms get to eat everything. Then the tube worms and forams (foraminifera) stretch out into the turbulent flow to catch food particles. Natural reef rock is covered with all this stuff in the periphyton which grows on the rocks (at least until it's lifted out into the air, which kills a lot of it.)......
