Honestly the only way to "sterilize" is not to kill the bacteria, but rather let the fishes defence system handle the virus/bacteiral infection.
Best way to accomplish this is feed that fish like mad! Watever food that fish will eat will only make it stronger.
I have uv, and it does not eliminate ich, ect.
Well after reading your post just now :lol: I realize your talking about cleaning the tank and not using uv. LOL. Anyways to kill the bacteria you can:
hydrogen peroxide it. Bleach it(i dont like that meathode, gotta use dechlorinator afterwatards)
For calcium build up vinigar or Muriatic acid(very strong 100x vinigar)