I'm rather over the top when it comes to QT I'm afraid. I keep one 30L running permanently as a QT for inverts and observation for fish that either have been medicated, or have come from a fellow reefers tank (thus assumed to be disease free). I then have two more 30L tanks that I press into service as needed as hospital tanks. Basically I keep a canister on my main display filled with those ceramic bio rings that I can use in a HOB filter on either or both of the hospital tanks. Generally when I need one, I run 20 gallons from my display, then dilute it down to 1.020 with RODI water. Once the new fish is home it generally just requires a bit more fiddling to match the salinity. Only exception I have found is Divers Den who ship fish at full salinity of 1.025. Hope that helps!