14 Sand Filter

The sand filter is a particle filter for small to large particles and should only be operated automatically. The filter material (quartz sand or similar) is passed through from top to bottom. The particles get caught between the sand grains, so that the required filter pressure increases. Time or pressure controlled, the filter is switched to flushing. Water flows from the bottom up, causing the sand bed to agitate and the filtered particles to be transported and removed from the system with the wastewater. The sand filter is used for large and largest aquariums. Alternatively, a drum filter can be used.

Due to the large surface area of the sand grains, the sand filter also serves as a biological filter. If this function should also be usable for small and medium aquariums, the filter should be operated as a fluidized bed filter. The water flows from the bottom to the top with a high water output, so that the sand grains are continuously in motion. Bacteria layers that are too thick are sheared off and leave the filter. The fluidized bed filter cannot become clogged, but it cannot filter particles either.