Normally in a freshwater aquarium most of us think of the biofilter as a way to convert Ammonia to a less toxic Nitrate. The Nitrate is then removed from the tank by means of water changes.
Actually the biofilter does much more than that. Nitrate, Phosphate, and Organics are only 3 of the many substances that the boiofilter processes. For the best freshwater aquarium biofilter information you will find in English read this topic: https://www.aquaticplantcentral.com/f...ted-dutch.html
The following video is about a product used to feed the biofilter microorganisms in such a way that they reduce Nitrate and Phosphate. http://www.youtube.com/watch?v=sLhmI8vtnfw
What is important to note in this video is:
1. The biofiltration is about converting Phosphate too
2. The biofilter performance depends on the water flow rate through the filter
3. The biofliter performance depends on the movement of the biomedia
4. Different factors can enhance or hinder the biofilter processes (in the video they talk about using a special food source to feed the biofliter microorganisms which makes them capable of making Nitrate and Phosphate "disappear" from the aquarium water)
If you read the translation from Dutch and watched the video you should be doing one thing right now: Questioning if your biofilter is setup and working as you want it to or "it just works and I'm not gonna touch it".
If you have started to understand how dynamic of a system a biofilter is you will start to understand how the best method to maintain a planted tank (ADA's) leaves room for improvement at least in the area of biofiltration. And you will start to see how flawed other approaches (EI, PPS) are.