UV Sterilizers are a safe, effective and proven method of water disinfection that can be easily adapted to any size application. Use of the proper size UV sterilizer kills parasites before they can cause disease! This cleansing light eliminates any free-floating bacteria, fungi, mold spores, viruses and protozoan (parasites) by preventing replication.
Ultraviolet disinfection is never used as the sole method of water treatment. At the very least, it should be accompanied by sediment pre-filtration to ensure that bacteria and viruses are not shielded from the UV light by particulates in the water.
UV Sterilization is the safest method of preventing and eliminating problems in an aquarium, or pond. Pond UV Sterilizers will not kill a parasite on the fish, but parasites go through a free floating stage, at which point they are eliminated.
Additionally, corals and fish can and do carry bacteria which can infect and spread throughout the pond, killing other inhabitants. The initial thinking on reef tanks was to avoid UV, to keep plankton alive. However, with the skimmers and pumps used on water garden ponds, the plankton population in the water column is virtually non existent. You can use a UV continuously (recommended) or just keep one at the ready, in the event of an outbreak.