Is this particular to the Vortech powerheads, or could I expect a similar problem with a Koralia nano? From the pictures I've seen, the Koralia powerheads seem to have a narrow "grille" around the propeller, except for the hole in the front and I don't see any shrimp being able to get in there while it's on.
It takes generosity to discover the whole through others. If you realize you are only a violin, you can open yourself up to the world by playing your role in the concert.
-Jacques Yves Cousteau