you may need to do a bit of homework into the make of this filter willo iit's important you do, why ?.... to make duobly sure that this filter is rated to this size pond,Ive got about 9000ltr (1979 uk gallons) pond. I was given the filters and there's no name on them so I don't know the make. The brushes and filter foams are new only 4 wks ago which is when everything got cleaned.
The pond is only 12 months old there's not much rubbish on bottom.
It may be you need to either upgrade it or add another onto it
Dave