I've done it twice with new tanks, but both times, I knew the tanks were coming, so added a bit of extra filter media into my cannisters and transferred that into the new cannister on the new tank. One of the tanks suffered a mini-cycle, but it only took about 4 days to clear up, and ammonia never went above 0.4 nitrite 0.1. Didn't lose any fish either. Anyway, it does work, just keep an eye on the tank for the first couple of weeks to make sure!!