i think what you are referring to is a plastic tube that contains ceramic magnets, these are made in various sizes and tank water flows through them plumbed into your return line....the company makes claims that water quality is greatly enhanced by the magnets which increases the orp levels similar to the use of ozone....i do not honestly know enough hard science to agree or disagree with such claims
Thanks so much guys! And yes it's for an aquarium 55g reef tank ,was looking for a protein swimmer and came across it saying it can replace a skimmer figured some reefer would have tried it guess not... Any suggestions on a protein skimmer for a 55g? Thanks......