The bacteria ON the bio-pellets are not free floating, so would not go through the UV, so no issues.
However: Are you re-populating the bacteria? Using microbacter or other?
If so, you should turn off UV for some period while adding that.
Lower flow through UV = better dwell time = kills larger bacteria and even some protozoa.
But it means less overall turnover.
Notes:
There is debate on killing bacteria being a good thing or not for a reef tank.
Simple UV like that is not going to eliminate the risk of ich.