That a UV can keep populations of parasites low? I’m confused by what your asking. What a UV does is make it so the current population of parasites that pass through the UV sterile (under correct flow). I never said it eradicates the population. I also never said it will stop the chances of your fish getting them… just lower them. If your fish is healthy, it will also help with fighting off parasites/infections.
I was only wondering if you knew of any controlled experiments that show that this is correct. This is the abstract from one article (in aquaculture - This was just published this year - and If I was using UV or Ozone - I would be sure to be aiming for the amounts listed in the article. (PS this is the article Jay Hemdal quotes below).
https://www.sciencedirect.com/science/article/abs/pii/S0044848621012618
Jay Hemdal had these comments in a different thread today: "
UV sterilizers
Ultraviolet (UV) sterilizers are also sold as a “cure” for
Cryptocaryon. The problem is that most hobbyist-sized UV sterilizers do not have the power to make an effective kill on the relatively large
Cryptocaryon parasite. Additionally, UV sterilizers are effective only on the tomite/theront stage, as this is the only point where the parasite is even present in the water column.
The fallacy here is that tomites/theronts
must leave the fish. Actually, some of them get caught up in the fish’s mucus and stay attached until they become infective trophonts again. This means that UV sterilization will not eliminate active
Cryptocaryon infections from a single aquarium. Where it does have benefit is in eliminating tomites as they pass through a filtration system from one discrete tank to another (like in a public aquarium or fisheries lab). Decades ago, diatom filters were touted as cures for ich and velvet. The same issue applies with them; there are adherent forms of these protozoans that can continue to infect the fish without ever having to leave the fish’s body. Even if they do, the “dwell time” factor means that some theronts will still be present in the water column to infect the fish.
A recent study (Ge-Ling, 2022) indicates that the UV dose required to kill Cryptocaryon theronts/tomites is 185,000 uw/S/cm2. They do go on however, to conclude: “ …both ozone and UV are ineffective in controlling infection within an individual aquarium because of the adhesive nature of
C. irritans tomonts (Ma et al., 2017). Therefore, the focus on UV and ozone treatment should prevent live theronts flow into aquaculture ponds. Second, the tomonts are strongly resistant to UV or ozone than theronts, implying that recommended production doses cannot wholly kill tomonts….”
EDIT
@Blindface It was my understanding that 1) the OP had fish with active infection and Thus - my comment that UV may not be that helpful in a 'treatment situation'.