DWC air pump and valves

Good to have a check valve in place. make the system redundant not problematic.

Like others have said should use it, but maybe space is an issue for you. So I’ll give you this, hydrostatic pressure works when the fluid is higher than the release point. So if pump is higher than bucket it would be impossible for it to backfill when the pumps off. But if something happens, say pump falls or hose disconnects and falls lower, you will have a mess.

Always use as many preventative measures as possible..............things can go wrong quickly, why risk everything for a .00 valve??

Good practice to install and use the one-way valves. Are you accounting for an exhaustive set of scenarios when hoping that placing it above water level will protect it? I could sit and think of a scenario with a power outage and some capillary action or siphoning effect which would result in water destroying your pump. Just use the valves. And add the pump filter to your weekly OpSec list.