Feed pump size for 4 post RO

[MillbrookMaple]

Anyone out there with a 4 post RO? I upgraded my old Eco Chem to four 8 inch posts last year. I'm using 2 non industry posts from Atlantic RO and 2 MES posts. I have a 7.5hp high pressure pump and my feed pump is 1HP. I feel like my feed pump might be undersized. If I have any little bit of plugging of the filter It causes the High pressure pump to starve and it shuts down. (System shuts off it feed pressure drops too much. It also barely keeps up with the rinse cycle when I have it set concentrate valve set to open. Just wanted to see what everyone else that runs a 4 post system has for a feed pump. Just in case it matters. First pass flow rates usually are about 3gpm of concentrate with 9-11gpm of permeate depending on teperature and starting brix.

[Bricklayer]

If you could find out the specs on your current pump and find the curve chart and what its max gpm is that would give you a starting point on what you got. You Probley need at least a pump that can do 20 gpm at 50 psi. That’s 1200 gph. But I’d go higher as that’s minimum in your setup. Wide open it’s Probley higher.

[MillbrookMaple]

Thank you. It looks like I'm probably better to upgrade to a 2hp unit. Looking around it seems a lot of systems that run 3 posts run a 2HP feed pump to a 7.5HP High pressure pump. I might buy another post with built in recirculation and get rid of my non-industry posts. They are fiberglass only rated to 300PSI so if I replaced them I think I'll gain system efficiency since it will have built in recirc for just that membrane and also I can run my system at higher PSI to squeeze out more. Anyone have any suggestions on a good 2HP feed pump to replace my 1hp with? I checked my relays and the one for the feed pump can be adjusted up to 15amps so I should be good to just swap pumps.