Nice post @Dewald, I cant wait to try it out this weekend. Quick couple of questions, does it have to be 2 bottles? is the bottom bottle (500l) acting as a way for some air to seep in to the 2 litre so as to not create a vacue, or is this just accopmlished buy the barbed adapters area (essentially a minute controlled leaking in of air)? Beats the way I was doing it with a pump to build pressure and force the water out, and then constantly having to adjust the air flow, ugh what a pain in the butt, this looks like way less maintenance.