LFS also just wants to sale you something to make more money. If she is using one, most of the people coming in who are new think they need it also.
UV really only helps on freshwater and when there is a micro problem.
In a reef system, they are not needed and really cause more harm than good. If using one on a reef system, they will kill off planton and micro algae needed in the tank.
I know, algae in the tank.. hmmmm. Yes you want some. Micro algae in the tank is a must in my opinion. This helps give something for the planton to feed on. There for keeping them alive and then the fish and coral also have planton to feed on. "circle of life"
So just like everyone else said, its not a needed item. Sometimes simple is better.
Also, just like it was said before, canister filters are not needed on reef tanks. They are nitrate factories on a reef tank (which you dont want high levels of nitrates)
Bio-balls are also nitrate factories.. they are a freshwater thing.. Not needed.
Sump if you can set one up
skimmer
life rock
return pump is all you need.
put in some plants, algae in your sump if you can. Have the rock hold the algae down.
types of algae and other plants...
http://www.aquacon.com/vip.html
run a light on your sump longer than you would the main tank. (I run my light on my sump when my main tank lights are off) almost double the amount of time.
This will help algae grow in the sump. There for the algae in the sump eats the nitrates in your system. helping keep your nitrates low. The more algae in your sump, the better in my opinion.
But a slamm amount at first. Run your lights, It will grow fast enough and will help your system.