A UV can be used on any tank with water in it.
Usually, water is supplied to the UV unit by a pump. The manufacturer should give a recommendation for the flow rate, so the pump can be sized correctly.
The manufacturer should also have a recommendation for what size tank it can be used with. (I have a 40 watt unit for a 210 gallon tank, but I have never used it yet).
The main question is what do you want the unit to accomplish?
UV sterilizers do have a time and place to be used. They are pretty good at clearing up a green water bloom or a bacterial bloom (where the target organisms are suspended in the water column). They can also REDUCE SOME parasites, but only if they are in the water and get pumped through the UV. They won't eliminate many parasites which spend part of their life cycle on the substrates of our tanks and part of their life cycle on our fish (corals).
UV units are generally not cheap. I don't know very many people who use them. They are typically low on the list of priorities for a reef since there are much more essential items to spend money on. They require frequent cleaning of the sleeves and frequent replacement of the bulb(s) to keep them in optimal condition.
I couldn't say anything about one specific brand over another, since I haven't used the one I have.
