As an aside, I find that the trick with the Paterson tanks is to press the centre of the soft top cap whilst lifting the edge a little to let the air escape. This leaves a slight negative pressure within the tank, which reduces leakage to a minimum. I quite agree about the Glug time govening the inversion rate, it's very important to give the liquid time to settle. In the 8 reel tank this is about 30 seconds.