I have a 100gpd BRS RODI and recently my water production has greatly slowed down. I have 55psi coming in and have changed all filters and DI. Im guessing its time for a new membrane...I would like to use a spectrapure, so which would be the best membrane to go to( 75, 90, 100 gpd)? I hear the 100 has a lower rejection rate and if i change from 100gpd what else will i need? Thanks!