Many hobbyists and professionals alike are concerned that using a UV sterilizer in a reef aquarium may be detrimental to coral health. The theory is that the sterilizer kills the living phytoplankton and micro algae spores that naturally grow both in the world’s oceans and our aquariums. This phytoplankton and micro algae spores are important to certain types of corals and are used as a source of nutrients. The concern is that UV will reduce or completely stop the aquarium’s production of these coral food sources, and will cause coral growth to retard or even stop and may even cause the coral to waste away.
Tropics recommends UV sterilizers for all aquariums including reef aquariums. The concerns mentioned previously are valid but one must understand the full implication of the argument to make a proper cost vs. benefit analysis. Tropics has run many SPS, LPS, Leather, Zoanthid, Clam and mixed reef aquariums over the years all with UV. The only corals that seem to suffer a slow down on growth rate with UV are Goniaporas, Gorgonians, and clams smaller than 1.5″. Supplemental feedings would be required to ensure proper growth and health. The home aquarium is too small to produce enough beneficial phytoplankton to keep these species well fed; clams will literally filter the aquarium water removing the phytoplankton. This means that with a few small clams you may be creating an environment that resembles what you would have while using a UV sterilizer, but you would not have any of the benefits of using UV. If you are currently supplementing your aquarium with any type of “coral food” then you should be using a UV sterilizer as you are already compensating for doing so by adding the supplement.
In Conclusion: If you choose to take on any of these species you will need to supplement the aquarium with a “coral food.” The aquarium cannot supply enough phytoplankton for these species with or without UV. Corals, just like fish, can benefit from an environment where bacteria and parasites are not able to reach plague-like proportions, and while we refer to a few corals that may be affected, the mass quantity of coral would not have any detrimental effects from UV.