Katadyn Silt Reduction Kit: For waters with high levels of suspended matter, e.g. in shallow anchorage, we would recommend you use an additional prefilter. This additional filter is finer (5 microns - 1 micron = 0.001 mm) than the standard filter (30 microns) and is placed after it. A booster water pump (12V/0.8 A/h) is also provided. This pump compensates the loss through the second filter and increases water production. We would also recommend the prefilter kit when the PowerSurvivor is not installed under the water line and when it is in constant use to increase the intervals between servicing. Includes all necessary fittings.