I am in a similar situation. I have a 10 gallon QT that I have used many times as I do a minimum 30 day quarantine on anything that enters my fishroom.
I finished quarantining a Falco Hawk about 3 weeks ago and am hopefully getting a Blue Chin Trigger this Friday. Will my bacteria have died in the QT since it has only had a piece of live rock with a few small corals on it for near a month or should it be good to go? The filtration is a hang on power filter with some matrix media originally from my DT.
If the bacteria has likely died, how much pure ammonia (I used pure ammonia to start my display tanks cycle) should I add to it the next time it sits empty to maintain the bacteria for the next round of quarantine? A drop per day, 2 drops per day?
I would like to keep it ready in case my trip to the LFS leads me to something I can not live without LOL. Of course, if during quarantine I find myself needing to use any meds, I would thoroughly clean everything with bleach and start over. My last two quarantines I have been very fortunate to get healthy individuals.
Sorry this was so long,
Troy