I've dumped the tank about five times! Maybe it's just me, but you have to grab the bottom cartridge ring or you end up unscrewing the tank from the ring and dumping the juice. My other tanks, two BCC Megas and an Innokin tank, don't have that ring, so when I'm switching between them, I absentmindedly forget to grab the Protank cartridge ring and there goes the juice. Very irritating to say the least. Otherwise, it works great.