that when using a remote pump with a long hose to the bilge bottom you would probably need a check valve on the bottom end to keep water from the hose run from running back into the bilge - sometimes it can be a significant amount on a deep bilge - at least for those who want to keep a fairly dry bilge. Check valves can be the cause of other problems though - as usual there is no perfect solution. I do have a check valve in my "big" electric bilge pumps hose (1 1/2" ) as it's a somewhat long run and can feed a lot of water back. In this photo you can see that my "big" (3700) pump mounts in a molded in hole in the very shallow sump - I like this idea from Voyager as it concentrates all the drips and dabs into the mini-sump thus keeping the bilge quite dry. (my icebox drains to the bilge or I would not have water to pump).