And they thought this question would get past me...
I will use plain English for this paragraph. UVs do NOT kill ick. They are great for viruses, bacteria, and algae, but ick is simply too large to be killed under normal applications.
Think of a tanning bed (which is UV). A flea, louse, etc will die at about the same time you are getting a sunburn. If you stay in a tanning bed for a day or two, the UV light will kill you.
Now the "semi-technical part"...
Most UV systems sold for aquariums have their flow rates based on a "zap" of 15,000 microwatts per sq. cm, per second. This is enough to kill almost all viruses, bacteria and unicellular algae. Fungi are larger, and need a longer contact time. Parasites are MUCH larger, and thus need a MUCH longer contact time. C. irritans (SW ick) needs a "zap of +/- 128,000 microwatts per sq. cm, per second to be killed. Thus, if your UV is rated for a 500gph pump, you would need to drop it to app. 55gph. Once a UV is slowed down that much the ick is probably reproducing faster than its being killed.
And with all due respect to readers...Before someone posts that I am wrong, call your UV's MANUFACTURER, and ask them the flow rate required by your UV to kill ick.