If you place live rock in your QT as you are asking, you will need to sanitize it afterwards, but I'm sure you understand that. I use bottled bacteria (Either instant ocean Biospira from Petco or Aqua Vitro Seed) to set up my QT with an ammonia checker so I can use an ammonia reducer if needed. Sometimes I stick a bio sphere or two in the filter as well so it's similar to your live rock question. Depending on what treatment you need to perform, read ahead of time as some treatments can't be used with an ammonia reducer. If you preplan you can leave a sponge for your QT filter in your sump until needed, once used and done with it, just throw it away. If you are in an emergency situation, I have an AquaClear 20 filter with a 3D printed filter box that you can have if you need it.