Cheap and effective UV sterilization does not currently co-exist. Either you're delivering a radiation dose at a total tank volume turnover high enough to disruption the target organism(s) life cycle OR you are not. There is no in between. The science behind UV's is very well understood but for some reason aquarium hobbyists insist upon not reviewing the available data, making correct choices and then bad mouth the concept when the process doesn't work. Save your money unless you find someone willing to part with either a 3" to 4" diameter unit with a new non-PC lamp of at least 25watts - 40w preferred. If you find such a beast call me and I'll calculate the correct flow rate for you to disrupt the life cycle of Cryptocaryon/Oödinium.
BTW, the info on the good Doctor's site is rubbish unless your target organism is floating single cell algae.