RO is great time saver. If you go to a 3 membrane set up, make sure you size your pump accordingly to get enough flow at high pressure (~100 psi on most 400 gpd membranes). Also I would highly recommend setting them up as a 2 stage set up. 2 in parallel and the third in series, combining the output of the 2 in parallel as its input. RO_Membrane_One_Two_Stage.jpg