+1 to Myka - get the drew's doser or the BRS two part ones (
may go back on sale on boxing day to 69.99 each as per black friday so hold off if you can. I dont believe doser's can back siphon just given their design (liquid is pinched out in one direction) It's not a free flowing tube so its not like the return line in your tank. I am going to use some snazzy VOGA wine bottles i have laying around as dosing containers;
