I've never been a fan of UV
filters. Not for ponds or for aquariums. Proper biology is more beneficial than sterile water, IMO
Two things to consider with your UV
sterilizer with the cycling rock questions.
First, the point of the cycle is to grow bacteria, not to kill it. Seems counterintuitive to me.
Second, most of the bacteria you're growing will be in the rock or on the container sides, not floating around the water column, so I don't see it actually affecting the cycle in any way.
As for the shock... sounds like there's a short in it, and current is getting into the water. While probably not a huge issue, it's certainly not a good thing.