thanks mate, makes me happy having it on my desk! The res has 3 ports bottom and 4 on top. One each connects to the centre tube and you would use one and block the other. Yes, Ive blocked the bottom and water coming back to the res comes in the top port which spills down the centre shaft. My inlet port is offset from the bottom. There is also a little clear plate sitting off the bottom to stop bubbles from going down the inlet. Linky here so you can see. Pretty neat I think!