Thanks for that jm123 are you saying i will have to do that every time to flush the merlin .I don,t have a float valve in my static tank i just turn off when tank is full ,but last night i blocked the product tube into static tank and it slowly started to fill pressure vessel i then turned off merlin and it slowly did flush .I thought these vessels were suppossed to fill at the same time as you were producing pure water into the static tank,not have turn the flow off from my static tank so as to fill pressure vessel.