Can anyone suggest a 24v pump...

[MapisM]

...with the following features:
1) sealed;
2) capable to suck most of the water from the flat surface at the bottom of a box;
3) with a sort of non-return valve, to stop the water from flowing back from the exit hose, as soon as the pump stops running.

No need for much power, it just has to cope with the shower and basin wastewater.

I'm asking because one of the grey water pumps in my boat went nuts, and I'm wondering if there's anything better to replace it.
Point 3 above would be particularly nice, because the exit hose is rather long, and all its content now returns to the collecting box after each discharge, leaving some smell in the forward section of the bilge - which occasionally can be felt also in the cabins.

Thanks in advance!

 

[jfm]

...with the following features:
1) sealed;
2) capable to suck most of the water from the flat surface at the bottom of a box;
3) with a sort of non-return valve, to stop the water from flowing back from the exit hose, as soon as the pump stops running.

No need for much power, it just has to cope with the shower and basin wastewater.

I'm asking because one of the grey water pumps in my boat went nuts, and I'm wondering if there's anything better to replace it.
Point 3 above would be particularly nice, because the exit hose is rather long, and all its content now returns to the collecting box after each discharge, leaving some smell in the forward section of the bilge - which occasionally can be felt also in the cabins.

Thanks in advance!

The little Whale gusher diaphragm pumps meet that exact spec, if you keep the inlet pipe reasonably short. However they do make a sound like someone breathing heavily underwater. I have one in my aft crew cabin shower sump and the noise is a bit annoying

 

[MapisM]

Many thanks J, keeping the inlet pipe short wouldn't be a problem.
And I'm not worried about the noise, which is just while using the shower or basin, anyway.
But is this one the thingie you're talking about?
I'm asking because this is what I found, but it's called "gulper" rather than "gusher"...