| Biofilm, especially mature established biofilm is very tenacious. It is very difficult to remove from media and will not easily wash away when backwashing a established mature bead filter.
With a brand new bead filter I would back wash only once or twice a week for the first few months until the biofilm gets a chance to establish.
With a mature bead filter I would reccomend backwash once a day if possible. If the backwash water seems pretty dirty backwash twice a day during peak feeding season and when preping koi for a show. |