[fkshiu]

I think UVs are good to have, but not essential.

The problem is that they efficacy is dependent on wattage and dwell time, so the best units are quite big. I don't think that the little UVs that most people have like coralife turbo-twists are all that effective.

You can't have too much flow going through too quickly because that would defeat the goal of maximizing the time the little beasties are exposed to the UV. If you don't want to add another pump, tee off a line from your return and put a true union valve on it. This will allow you to adjust the flow through the UV and make for easier removal for maintenance.

And don't expect a UV to "cure" ich - it may hold it at bay, but the majority of parasites remain either on the fish on in the substrate rather to remaining in the water column.