What to do about "Blocks with media errors"

I have a RAID5 with 4x 3TB WD RED drives, on a ASUS H87i-PLUS using the Intel RST RAID options

I recently encountered two power failures because of broken powerlines. After this event the RAID has been "Verified and Repaired" where it found 10 errors and repaired all 10 errors.

After this i now have 5320 Blocks with Media Errors

so my question is, what should i do about it ?

I've run Windows CheckDisk which came back empty handed - no errors..

I've now clicked on Verify again, with the option "Repair automatically" checked... (i remember doing that the last time too??)

thanksi