Homemade RO volume & pressure question

[Rick M]

After going back forth over the last few seasons on whether or not I should build a homemade Mattatuck Maple style RO setup, I bit the bullet over the winter, researched it the best I could and built a homemade RO. I started with an Aquatec 8800 pump to a standard household 5 micron water filter. From the filter the sap goes to a the first of 3 150GPD household RO membranes. The water (permeate) from the first membrane is sent to waste the concentrate from the first membrane becomes the input to the second membrane and so on for the third. I have a 1/4” needle valve at the end of the concentrate line in order to gate the output flow and regulate the operating pressure.

So after I assembled everything I decided to run a few pails of tap water through the system to test for leaks and flush the system out before I started running sap this week. From everything I read I should try to keep the pressure around 100psi (controlled w/ the needle valve) and the output volume between the permeate and concentrate should be equal.

My concern is that I can only get the pressure up to 80-85 psi, but the concentrate line is flowing about 1:4 ratio to permeate. If I open the needle valve the pressure drops to around 60 psi, but my flow volume is equal. I,m worried that if the vilune isn’t equal, I’ll be sending concentrate to waste, or if the pressure is too low the system isn’t doing its job as it shoukd and not filtering out enough water.

If anyone had similar setups and would be willing to give me pointers to help me get this thing dialed in, or at least pointed in the right direction I’d be very grateful.

[DRoseum]

The pressure when running water thru the system will be lower than when you run sap through. When you run sap, you will hit 100 psi without a problem.

[ecolbeck]

Also the only way that "concentrate is sent to waste" is if the membranes are worn out after several years of use.

[Hunt4sap]

My ears are perked up!!!( I'm just getting all mine put together)
Same components...

[Hunt4sap]

After going back forth over the last few seasons on whether or not I should build a homemade Mattatuck Maple style RO setup, I bit the bullet over the winter, researched it the best I could and built a homemade RO. I started with an Aquatec 8800 pump to a standard household 5 micron water filter. From the filter the sap goes to a the first of 3 150GPD household RO membranes. The water (permeate) from the first membrane is sent to waste the concentrate from the first membrane becomes the input to the second membrane and so on for the third. I have a 1/4” needle valve at the end of the concentrate line in order to gate the output flow and regulate the operating pressure.

So after I assembled everything I decided to run a few pails of tap water through the system to test for leaks and flush the system out before I started running sap this week. From everything I read I should try to keep the pressure around 100psi (controlled w/ the needle valve) and the output volume between the permeate and concentrate should be equal.

My concern is that I can only get the pressure up to 80-85 psi, but the concentrate line is flowing about 1:4 ratio to permeate. If I open the needle valve the pressure drops to around 60 psi, but my flow volume is equal. I,m worried that if the vilune isn’t equal, I’ll be sending concentrate to waste, or if the pressure is too low the system isn’t doing its job as it shoukd and not filtering out enough water.

If anyone had similar setups and would be willing to give me pointers to help me get this thing dialed in, or at least pointed in the right direction I’d be very grateful.

When you built yours what size pex pipe did you use? (3/8" or 1/4"?)

[Rick M]

Thank you for the reassurance, I think I’m on the right track...we’ll see toward the end of the week when I run it.

Hunt4sap ~ I used all 1/4” OD flexible plastic tubing & stab / shark bite connections