Due to calcareous content in the water or deciduous plants in the vicinity of the Piscina Biológica there might be a build-up of sediment at the bottom of the swimming part. Cleaning of this area is recommended every fortnight until monthly through a pool cleaner.
Usually plants do not need maintenance, because the old parts can fall into the water, they will be mineralized with the time and they are part of the feeding of new plants.
Never add any chemicals to the water. It is also not possible or necessary to use any disinfection equipment.