Don't have Tunze, so cannot comment. On the vortech, they come (or you can buy separately) with a foam sleeve that fits around the outside of the wetside to prevent anything from being drawn in an minced up by the prop. Foam does not cover the output. Running one without the cover, if you keep anemones is a risk, but the foam covers are also a pain because they clog up rapidly and reduce flow from the pump. Personally, I do not use them. Never had an anemone get pureed, but have lost a couple of fish.