I wouldn't rely on UV. There are MANY postings online and articles written about the topic, just do an internet search on it to find them. The UV systems on the market for most aquariums are sized in general to kill waterborne bacteria and viruses and are not strong enough to have a significant impact on ich. And the larger UV systems would only affect one of the life stages of ich, the free floating, and only those which actually make it into the UV system, not all of them. There are more effective ways to kill and keep ich out of your system.