Having a screen over the overflow would prevent that... and be easy to clean (just wipe your finger over it)
Do you have a suggestion for the intake that is about 20" deep? That is my main concern that drove me to the full coverage idea space.
Having a screen over the overflow would prevent that... and be easy to clean (just wipe your finger over it)
I can understand that.
However, in truth nothing you can do will completely keep the shrimp out. I have a prefilter sponge on the intake for all my tanks with shrimp and canisters. Still end up with shrimp in them unless the sponge is super tight, and then it blocks up and has to be removed and rinsed frequently to prevent it from slowing the flow. Shrimp mostly avoid being sucked in--they're used to a brisk current. The ones that end up in the filter seem to do just fine until I get around to cleaning it out and net them back in to the tank.
I expect the shrimp can handle a trip through the filter, but not necessarily through the impeller of the return pump.
so long as there's plenty of filter media and water, they should be able to live in the sump with little problem.
You should be able to more readily put the sponge filtration between the water entering the sump and the pump--most wet dry setups are designed for this, since you don't want there to be solids going through the pump anyway.