Get the installation right, this is somewhat critical to good operation. Once working correctly, they are nearly problem free. When you install, be careful to follow their directions. Particularly, the pump must be pointed up (sideways *will not work*), and its elevation relative to the bowl is important - just above the rim, not too far above.

Every other marine manual head has sliding or rotating seals, a bunch of moving parts flooded with effluent, expensive repair parts, tiny orifices through which your dinner is expected to pass.