JennM;986465 wrote: So something can spread? Yeah I'd like to hear more about that, sounds fishy to me (Pardon the pun...)
A UV can be a beneficial part of an overall life support system. It is NOT necessarily a must-have, but if you keep fish prone to ectoparasites, it can help mitigate risk.
What it isn't, is magic.
Sometimes people battle infestations and buy a UV thinking it's the magic smoke to make everything, all better. It isn't.
It will kill nuisance algae suspended in the water, if they pass through the UV (and the UV is properly sized, with the right amount of flow through it.) It won't kill the hair algae growing on your rocks.
It will kill free-swimming parasites IF they pass through the UV and it's properly sized with the right flow. It will not kill what is on the fish, what is in the substrate, and what doesn't get drawn through the UV.
It will not prevent either type of pest from happening in the first place. It will not make either type of pest completely go away. It will help control both types of pest, and will work BEST if used as part of a holistic approach.
Got algae? Solve the excess nutrient problem.
Got parasites? Solve the source of the problem with proper quarantine and treatment if indicated, low stress, good food and water quality.
UV will enhance the cure to those issues once the root causes are addressed.
Jenn