I set up the quarantine tank with sg to match or be lower than the bag water. After temp acclimation( floating the closed bag for 20 minutes), the bag is opened and the fishis immediately put in the qt.Basically I acclimate the tank to the fish rather than risking a long stay in bag water where ammonia toxicity can increase once the bag is opened particularly if fish have been confined to it overnight or longer as is usually the case with shipped fish. For fish acquired locally, I set the sg a couple of points lower than the store. For shipped fish I set the sg low around 1.017 in the qt since most shippers use low sg water for shipping and I can't rally know what the sg is without opening the bag. Drops in sg that don't go below their internal sg (1.008) don't stress the fish; rapid rises do.Some folks try to adjust the ph to match too ;I don't worry with it as long as my qt is in normal range 7.8 to 8.3 or so. The q tank is equipped with a sponge filter ,an airstone, a small hang on th back filter runing carbon , a heater and some pvc for resting places. In a three day time span ammonia buildup is rarely an issue but I use some ammo lock,ammonia detoxifier just in case.
I perform tank transfer 4x ,3 days a part for prophylacitc treatment of cryptocaryon irritans(ich). That is ; I move the fish every 3 days to a new tank for a total of 4 transfers. Along the way I gradually (.001 pr day) adjust sg upward as necessary to match the display tank water.I usually use 2 tanks(ten or 29 gallons depending on the size and number of fish) and dry them and associated equipment thoroughly before reuse. Ich will survive in wetness.
During this period, I observe the fish closely for signs of brooklynella, velvet( amyloodinium, flukes and any bacterial infection,etc. and initiate treatment when needed.
Thanks for asking.