Before I can give any sense of an accurate answer I need a little background information. First thing to know is, are you looking to design a system or are you working with an existing system.
If it is an existing system detailed information on the bed capacity, needed flow rates, water quality coming in (feedwater), any storage tanks piped in and any other information.
I currently provide support to a Ultra Pure Water plant that supplies a semi-conductor plant so I have some experience with large scale (300-600gpm) MMF and carbon filteration systems as part of an UPW DI makeup system.
If you are looking to build a new system from scratch I can give you a few ideas but for the best information contact me via the CR4 mailbox and I will get you the contact info people that desing and build this stuff for a living.