If you are just circulating the water through the tank and/or wet/dry sump, the only pods that might be killed are those that are free floating/swimming and that is not very likely. If you have a refugium and are UV'ing the water from it and returning it to the tank, you might be killing them there too (if the pump didn't) on their way back to the tank. The UV itself is only effective against organisms/algae that actually pass through the unit,... it does not do anything to the water that would residually kill pods. I have UV on all our tanks and even ozone on some and I don't believe it has changed the population at all. Depending on how much food they get and how much predation (by your fish) is going on, you may well see a fluctuation in the pod population. JMO
Doug