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.)

Here, our DROP1.4 scrubber® has been running for months in a saltwater reef pond, and was never cleaned. So the life developed naturally in it, and consumed the algae as fast as it grew which is why there is not much growth visible. If you want natural food production, this is how to do it. But only do it with an upflow scrubber, because a waterfall will let go of the growth down the drain.

For filtering, you would want to clean/harvest periodically and not let it continue to grow. Cleaning, especially in freshwater, removes most of the pods so there is less consumers of the growth, and thus more growth to absorb nutrients.

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