UVCs or Ultra Violet Clarifiers are basically little extra units that stop your pond water turning green. They have a special light bulb inside that gives out Ultra Violet light (hidden away so it can't melt your eyeballs!) and this UV light sterilises all sorts of organisms in the water as it passes through the UV unit. The UV light damages algae cells, meaning they can't multiply and they end up dying and clumping together so they get trapped in the filter sponges. This guarantees your water stays crystal clear without you having to faff around draining and refilling the pond or sloshing in expensive treatments once a week in summer.
Need help choosing?
You only need one of these UV units if your filter doesn't already have one built-in, or if you want to add an extra one to make your filter system more efficient. If you don't already have a filter, head over to the pond filter section and buy one - just getting a UV unit on its own won't help you as there is nothing to sieve out the algae cells after they've been nuked. The Vitronic units are simple but effective and can be added on to pretty much any pond by slotting them between the pump and the filter (so dirty water is pumped from the pond, into the UV and then into the filter sponges). If your budget allows, the Bitron C range is a top-of-the-line easy-maintenance alternative with a self-cleaning rotor to keep the quartz sleeve clear.