The MidiPond 20000 is a popular box pond filter that featuresa 7 stage filtration system. It is suitable for ponds up to 20000L without fish. See the size chart below based to determine suitability based on your pond setup.It features a UV light to help kill green water algae, a hinged lid for easy cleaning and multi stage media for optimum water clearning. Filtering stage overview: Spray bar oxygenates water creating the ideal environment for friendly bacteria. Graded foam filter pads remove dirt and waste. Ceramic biological filter media prevents the build up of harmful toxins in the pond.Replaceable polymer wool pads removes fine waste particles and polishes the water.Carbon impregnated pad removes chemical pollutants. Features: Comes with 18w UV bulb. Low maintenance and easy to clean. Spray bar oxygenates water creating the ideal environment for friendly bacteria. Seven stage filter design. Bio-media and polymer carbon cartridge. Hinged lid allows easy access for cleaning. Flow rate: 5000 Lph Max pond size (without fish): 20000L Recommended Hose sizes: Filter inlet hose from pump: 32mm / 1.25\" Filter outlet hoseto pump: 3 x 40mm / 1.5\" Pond Capacity Guide: Over 75cm deep without fish in shade Over 75cm deep with fish in shade Under 75cm deep with fish in shade Over 75cm deep with fish in full sun Under 75cm deep with fish in full sun Under 75cm deep with koi in full sun 20000 ltrs /4399 gal 10000ltrs /2200 gal 7500 ltrs / 1650 gal 7500 ltrs / 1650 gal 5625ltrs / 1237 gal 2810ltrs /618 gal