I've heard many opinions and they all seem to float around the idea saying that UV
sterilizers shouldn't be used as a replacement to good tank maintenance and care. They can easily be used to hide issues like algae outbreaks but you should always try to rectify the underlying issues. You also have to watch out for UV
Clarifiers vs UV
Sterilizers as the way they are marketed are usually misleading.
the clarifiers are less powerful and may only be good enough to keep your water looking clear while the stronger sterilizers can actually help with parasite reduction. in the end I think it's a totally optional piece of equipment at least at this point