[Timfish]

The most effective way to remove the hatching larva parasites is to have an appropriately sized dedicated pump supplying the UV at teh bottom behind the aquascaping where the larva are most likely going to be hatching out. Will it work configured differently and sharing a pump with other stuff, certainly. Using one, two or more small 9 watt or 13 watt submersable UV sterilizers is another workable option as well.

The reasoning for having the intake behind the aquascaping is when the aduilt parasites drop off the fish they have to find a place to form a cyct that allows them to go through the reproductive process. They will have to compete with algae, biofilms, sponges, corals and other stuff to find a space to attach to the substrate, this is more likely going to be behind the rock. They are also less likely going to be removed by algae eaters scraping the rock. As they larva hatch out they the slower currents behind the rock presumably lets them find and attach to fish easier. Another consideration is fish are more likely to rest or swim slower behind the rock.