"Only a small sump was employed, and water from the display tank passed through the sump rather slowly -- approximately once per hour. This also resulted in a slow rate of feeding water to the skimmer, which repeatedly recirculated water from the sump and may have helped in keeping nutrients and dissolved organics low. A large fish load was not kept in the tank, and thre was virtually no algae growth, with the exception of some calcareous algae that appeared on the intake to the skimmer box. These conditions -- low nutrients and the absence of nuisance algae -- have proved to be critical for success with SPS corals."