live rock sump and skimmer, which mean little in disease and parasite control(except for maybe stres by adding hiding places and water quality and enviroment) lets n ot forget stress does play a big part in these areas
careful stocking(again stress amoung inhabitants due to incompatibility and crowdedness)
and more imprtant for disease control and curing would be a hospital/quarentine tank, these are IMO an almost vital tool, whcih does do a lot in prevention and curing, are much les expensive and more versatile meaning that not only possibly helping with parasites, also can help with diseases and wounds
now as for the uv, one thing i must add is i belive they actually play litle role in preventing parasites, since they can almost definitely be avoided through proper care and preventative maintenance, I HAVE NEVER SEEN ICK so it is hard to convince me that an expensive piece of equipment is the only way to go if you do not want them, often ick is introduced or induced by stress and/or less than cautious stocking measures
again, proper water quality and careful stocking used with a qtank(can be made for under 50$)/hospital tank, IMO would go much farther and leave more $$ for my tank itself(like lighting, a skimmer, or livestock or lr and corals, you name it)