No. A sump is not a filter. But, you can utilize chambers in a sump to filter. A wet/dry filter can be made, which is similar to a sump (one could even consider it a type of sump), which is a great bio/mechanical filter. In a SW
tank, a refugium is usually built in a sump to provide a place for macro algae and things of that nature. It's also a great place to grow pods
. In a FW
system, you usually have the wet/dry setup. It can cause nitrate problems if not cleaned regularly, though.
Moved to General Hardware/Equipment Discussion