RO/DI Dual Membrane Question

T

TiberianSun

Premium Member
Quick question. We run a 75GPD RO/DI setup which I expanded to include a dual membrane setup (another 75GPD membrane). The original membrane was about 1.5 years old so I swapped it our for a 150GPD membrane. Is it okay to mix & match the membranes? Basically I have a 150GPD membrane that is new connected to a 75GPD membrane that is about 12 months old.
 
No, because the flow restrictor needs to match the membrane.
 
Agreed, in a dual membrane setup, both need to have identical GPD flow rates with a matching restrictor.
 
Thanks guys. So with my setup originally having a 75 GPD membrane would it be okay for me to buy another 150GPD membrane to replace the older 75GPD? This would leave me with 2 150GPD membranes. For me to do water changes it takes 150-160 gallons of water. The flow restrictor that is on the dump line is a 600.
 
You need the matching flow restrictor for the two membranes you plan to use. If you are running two 150gpd membranes, you can expect 12.5g per hour. That speed of membrane has a lower rejection rate, so DI resin is used up more quickly. If you want efficiency, you want two 75gpd membranes (98% rejection rate), which comes out to 6.25gph.
 
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