I had a thread a week ago on were my ro booster pump should be on one of the web sites.It said it should be between my last prefilter and membranes. So many had it off the tap and the first prefilter. Many thought it would make no differance. Vadim said between the prefilter and membrane.> Well happy to report I changed and guess what its improved my flow to double the rate ooo tbs and the less waste.Job down I am happy.Would love a beter pump but I will just have to wait.