Once your juice drops below a certain level, owith my protank 2 that level is about 50 % you'll get a leak from the 510 connection. It has to do with air pressure. You have to either top it off or open up the bottom and burp it to equalize the pressure. If you don't top it off it will leak again, you'll get a few good capes but have to burp it constantly. Heat and cold will also effect the tank and make it leak. Dont leave it in your car on a hot day, you'll have a mess when you get back to it. And when it has leaked, after doing one of the above, best way to clear the gurgle is to turn the tank upside down and blow up with air against the 510 instead of juice