These rotary vane air compressor kits pump considerably more air than the pumps above. Rotary vane pumps do not operate as deep as the diaphragm and piston pumps — maximum operating depth is 18'. A 3/4 HP high pressure model is available which operates to a depth of 27'. The 1/4  HP model pumps 4.2 CFM of air compared to 1.5 CFM with the 1/4 HP piston compressor. This larger volume of air will increase circulation and oxygen levels for faster cleaning of the pond's bottom. The 1/4 HP rotary vane kit is recommended for ponds from 1 to 2 acres, but often is used in ponds less than 1 acre if high fish population, exceptionally poor water conditions or heavy nutrient buildup exists. The 3/4 hp. models are recommended for ponds 2 to 4 acres while the 1 HP is used in ponds larger than 3 acres.