Acropora White Bugs

I have been experiencing random STN deaths over the past four months and a bunch of my acropora have lost color and have no polyp extension. I thought it may have been a stray volt so I replaced all of my heaters which did not fix the issue. Next, I dosed two types of bacteria, this did not help as well. I also tried replacing all of my RO filters and membrane which did not help either. Finally I found the culprit. I found these little white copepod looking bugs running all over the acropora tissue. The seem to stress the coral out by eating the polyps which causes the poor coloration, polyp retraction, and STN which eventually leads to the coral death. I tried dosing 1/2 tablet of the chewable Interceptor (expiration date November 2016) to the 120 gallon display and 1/2 tablet for the 160 gallon frag tank. After 24 hours I did see better polyp extension but the bugs were still on the corals. I then tried 1 tablet of the original Interceptor non chewable tablet (expiration date November 2007) for the 120 gallon display and 1 tablet for the 160 gallon frag tank. The next day I could still see the bugs moving around the corals. I dosed 2 tablets of milbemycin oxide/lufenuron for the 120 gallon display and 2 tablets for the 160 gallon frag tank (expiration date May 2021).