there is also a flaw with this, if you had a bunch of saltwater going through, the salt would eventually clog it, since it piles at the bottom, and would stop any more water getting through, i just don't think this could work, sorry.
I like this idea. @cracker64. there is an easy fix for the salt clogging the wall, all that would have to be done is put a void system up so the salt disapears or use portal if you want to move it somewhere. people would figure out how to do it pretty fast in my opinion. i have been wanting something like this for a while.