"Various public and private aquaria have used algae scrubber filters on their reef aquaria, with disastrous results. The microcosm at the Smithsonain Institution has yet to keep scleractinia alive for more than a year. While Dr. Adey has stated how well corals grow in this system, those viewing the system have failed to find these corals. In an interview with Jill Johnson, one of the techs responsible for the Smithsonian tank, she stated to Frank M. Greco that frequent collecting trips were needed to keep the system stocked with live scleractinia."
From http://www.seasky.org/aquarium/aquarium_faq_page02.html#2.9