4x40 RO build sprinkler pump

[Reister]

Long time reader first time posting on MT. I've seen all the 4x40 RO builds on YouTube and read most of the threads on here. My question come from a recent YouTube video in which a person was using just 2 sprinkler pumps to feed the I think 2 RO membranes. My thought is if you have enough volume does that make up for less pressure? Can you just not get as high of concentrate with low pressure? I like the idea since to have 2 sprinkler pumps instead of a procon mainly for energy consumption. I'm off grid and will run a generator when needed. Sorry I'm not try to reinvent the wheel, more thinking the KISS method.

[darkmachine]

I might have seen the video you're talking about, lower pressure higher volume. I think with any setup that doesn't use a high pressure pump you'd likely need to recirculate your concentrate back into your sap tank and feed your permeate into storage tank, that way you'll get multiple passes and your tank will gradually get sweeter and sweeter.

[Rselleck91]

What do you need out of your ro is the question. That guy doesn’t really show his permeate coming out. Your standard 4” membrane has an operating range of up to 600psi. Here’s the most important part, each membrane needs at least 100 gallons of permeate to wash properly but 150 is desired and you need to wash after pretty much every cycle. So in that build 200 gallons needed minimally. 100psi would get you there painfully slow. You will always be wishing you were running a high pressure pump at 250psi. You would get more output out of a ro bucket setup

[maple flats]

Read the specs on the sprinkler pump you're considering. Most 4x40's run at least 200 psi, many run at almost 300 psi. While a 4x40 membrane will perform at lower pressures, under 200 psi will severely reduce the gph it will do. My 250, runs at 275-280 and does about 250 gph removing between about 75% of the water.
If you are fine with maybe 1/2 or even 1/3 of that a sprinkler pump may be the ticket for now. As you get to where you need more, change the pump to one that will give you more gph and more pressure. The same membrane will be good.
If you have a single 4x40, you should get about half what my 250 gets once you go with a better pump, but still 1/2 or 1/3 of a 125 may be just the ticket until you get bigger or need better water removal.