Thad, thanks for the input. I Was thinking that this machine would do more than what i wanted, but I didn't want to push too hard with the pressures. This new machine is replacing a 20 year old Coster machine with 2 membranes (8inch). Could put about 850 gph through it. 2 to 8% at about 3.5 gpm but at350 psi at best. usually 400 to 450+ psi. I hope to be able to obtain the numbers you are talking about. do you have any preidictions of the pressures I will be running if I attempt theses numbers?