25l biofilter (pressurised) with a 15W U/V combination filter. Typically 100 to 150l/min flow rate and good for smaller ponds up to a maximum of 12,000l stocked at hobbyist levels of fish. Bio filters pond capacity is indicative only – if unsure always buy the next biggest version. You can never ‘over do’ biological filtration, and you never want to ‘under do’ it either. Includes around 350 bio balls.