Pressure filters are highly recommended for your pond. They're easy to conceal (you can literally bury the majority of the filter behind your water feature - just leaving the top above ground level for maintenance), they provide great mechanical and biological filtration, and they nearly always include an integrated UVC (Ultra Violet Clarifier). We have pressure filters suitable for ponds between 2,500lts and 40,000lts, with products manufactured by Blagdon, Fish Mate, Green Genie, Oase, Laguna and Velda.