I am planning to set up a planted aquarium, which has led me to some questions. I'm a bit puzzled about filtration in aquariums in which plants are the focus. There are several reasons to use filtration for a planted aquarium. First, and probably most importantly, it provides water movement.
Plants are able to take up nutrients much more efficiently in at least gently flowing water.
Water movement also prevents suspended particles from landing on plant leaves where they can interfere with photosynthesis. Even if the flow is set low, it will keep particulates from settling on the substrate, so they can remain in circulation and be removed by the filter. As we know, in addition to water movement, that filters can provide mechanical, chemical and biological filtration. Most people who keep fish in their tanks want some mechanical filtration. Leftover fish food, fish wastes and dead plant materials all contribute to detritus in the tank.