Suction/Strainer Filters: Positioned in the reservoir or pump's intake. This filters primary function is to eliminate contaminants before they reach the pump. Many suction strainers are constructed with a bypass valve to avoid pump cavitation when the filter gets clogged. Typically, suction strainers are constructed with coarser wire mesh media, threaded endcaps, and are installed inside the reservoir. On the input side of the pump, a Suction filter is a cartridge style made of wire mesh and even cellulose or microglass.