Reverse Osmosis pressure

AJ, while you're here, a related question.

Does rejection/production scale linearly with pressure? Underlying question is, if a flow regulator was trimmed for 4:1 @ 40psi, will it still be sized right @ 80psi (or is a new flow regulator required)?

 

I'm glad you mentioned that, I was actually wondering if that was possible.
I am still trying to figure this whole thing out as I am new to reverse osmosis and reef aquariums.
Why does a dual membrane system need much more PSI to operate efficiently?

If a dual membrane system truly needs atleast 60psi, why does the manufacture (Spectrapure) state in their manual that it needs 40-80psi and not 60-80 psi?

If I leave it as is with 2 membranes shouldn't that take more of the load off of the DI filter?

I don't think I am understanding the difference between having 1 and 2 membranes and less and more pressure needed for each. Is the water being split between the two membranes and not necessarily going through both of them?

 

Dual membrane systems are plumbed differently than a single membrane system. They take the brine or waste from the first membrane and feed it into the second membrane so there is a pressure loss or drop to the second membrane.

Their Owners Manual is written to cover several different models of systems so some things such as the pressure are generalized. If you look in all the reef forums they sponsor or on their own forums they have always recommended a meinimum of 65 psi for a dual membrane system from day one. I had mine over 10 years ago and that was the number then also. Most people who invest in custom systems such as dual membranes, MaxCaps and such contact Spectrapure before buying and the techs always ask particulars like your pressure, TDS, how you intend to plumb it etc. I actually had them customize the previous systems I had from them with things like an ASOV and isolation for the DI so I could use the same system for pressurized drinking water, home brewing and ice maker as well as have DI for the reefs.

evolved, both temperature and pressure will change the waste ratio and required length of the flow restrictor. If you check at different pressures you will see a change same as at different seasons of the year where you experience changes in water temperature. I actually have two restrictors, one trimmed for colder(if you can call Phoenix colder!) winter water and one for warmer summer water that I can swap out as needed to keep things efficient if I choose to.