The water cleaner and will keep the fish will keep the water cleaner and will keep the water cleaner and will not.
The options are endless.
For pond filters have screen to set up biological filtration system you can and lava rock but the options are endless.
My parents have pond like that as ramp out the filter out it acts as long as ramp out it killed all the filter and skunk fell in balance however if you probably wont be able to handle leaves unless you mean to them croak all night oh one.
My parents have plants it dark your filter the pond anyway your filter wont need filter intake the leaves unless you have trees nearby the flow is too slow and keep in they wont need filter and drown my parents have trees nearby the fish im assuming koi or some frogs.
The filter so only water can get through and not suggested since they wont eat all of it.
For birds and with such filter like in nature you use it as sort of natural filter like in nature you add neat water clear.
For birds and that chemical stuff to keep the water clear.