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Thread: Disappointed in my homemade RO and need advice

  1. #1
    Join Date
    Jan 2016
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    Cromwell, MN
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    36

    Default Disappointed in my homemade RO and need advice

    I finally made the plunge and purchased the supplies to make an RO which I was able to try out today. I知 running 2 400gpd membranes in parallel with an aquatec 8800 pump. I知 able to run around 100psi but I知 only making about 1.25 gal of ro water per hour. That rate seems very low to me, what are some factors that could be causing a slow rate like that? I do have a pair of drips to take care of but they don稚 amount to much volume.
    2017 - 45 taps on buckets 260gal sap 6gal syrup
    2018 - 92 taps on bags

    All boiled on a homemade 2x5 fuel oil evaporator using 6 steam pans

  2. #2
    Join Date
    Feb 2017
    Location
    NY
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    51

    Default

    Send a pic. Are you using a variable flow
    Restrictor? When you say 1.25 gph permeate, do you mean 1.25 gph if concentrate as well (are you running it at 50/50). Those numbers are super low.


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  3. #3
    Join Date
    Feb 2017
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    Upper Valley, NH
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    How much is coming out your permeate line, and how much is coming out of your concentrate line (per hour)? Do you have a needle valve on your concentrate line after the membranes? If they are in parallel, are the membrane outflows combined before the needle valve so you are putting equal pressure across each? You should be able to process 10-15-gal per hour at 50/50 with that setup. I would suggest using them in series rather than parallel.
    110 Taps on 3/16" "natural vac"
    Leader Half-Pint Supreme with AUF
    Souped-up RO Bucket
    3 Black Rescue Dogs
    A Dozen Bee Hives
    A Flock of Icelandic Chickens
    30 Acres of Wooded Bliss
    https://blackdogbeesandmapletrees.com

  4. #4
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    Apr 2012
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    poultney vermont
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    It's pretty simple you're not running enough pressure. In order for a membrane to work you have to force the water through a core of mesh and fibers and all kinds of stuff. That has a lot of resistance it takes pressure to overcome this resistance. The more pressure you apply the more flow you will get. Of course the more pressure you apply the more chances you get to foul up your membrane and must be vigilant about cleaning. most people run around 400 lb never over 500.

    You're going to want to beef up your pump your lines in the whole system to handle more pressure
    18x30 sugarshack
    3500 taps high vac
    3x10 inferno with steampan
    7'' wes fab filter press
    D&G 1000
    300&400 gal stainless concentrate tank
    1-2500
    3-1550's
    4-275's
    more taps to come in '19

  5. #5
    Join Date
    Feb 2017
    Location
    Upper Valley, NH
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    I wouldn't try putting 400psi across those 400gpd membranes or you'll have a disaster on your hands. Those are likely designed for 150psi. But everything needs to be balanced and your pumps need to match your membranes needs to match the housing max pressure needs to match your fittings, tubing, etc., etc.... Then crank it up and like Bliss said, wash your membranes often to keep 'em from fouling.
    110 Taps on 3/16" "natural vac"
    Leader Half-Pint Supreme with AUF
    Souped-up RO Bucket
    3 Black Rescue Dogs
    A Dozen Bee Hives
    A Flock of Icelandic Chickens
    30 Acres of Wooded Bliss
    https://blackdogbeesandmapletrees.com

  6. #6
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    Apr 2012
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    poultney vermont
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    I guess I am not familiar with membranes other than 8" CDL, filmtec, hydronautics, I'm not so familiar with the small hobby machines.....these can all take 400 psi. You can usually find a cut sheet (spec sheet) that tells you max pressure, max pH, rejection rates etc....
    18x30 sugarshack
    3500 taps high vac
    3x10 inferno with steampan
    7'' wes fab filter press
    D&G 1000
    300&400 gal stainless concentrate tank
    1-2500
    3-1550's
    4-275's
    more taps to come in '19

  7. #7
    Join Date
    Feb 2017
    Location
    NY
    Posts
    51

    Default

    His pressure is fine, but being that he is running 2 membranes in parallel he is probably restricting to nearly no flow to achieve that pressure. The aquatec 8800
    Can’t really handle 2 400’s in parallel. Not sure if OP is still around anyways!


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  8. #8
    Join Date
    Feb 2019
    Location
    Murrysville, Pennsylvania
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    104

    Default

    I run two 400 gpd membranes on the aquatec 8852 pump at 100 psi without a problem. I have those feeding into a 3rd membrane and was really happy with its performance this year. Was probably running around 15 or more gallons of raw saw per hour thru it to get around 4 gallons of concentrate depending upon sap temps. Some warmer days was able to get thru 50+ gallons in about 3 hours or so.

  9. #9
    Join Date
    Jan 2016
    Location
    Cromwell, MN
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    36

    Default

    Sorry guys! I got locked out of my account and got busy with COVID issues.

    IMG_6663.jpg

    There is an image of my set up. The system seems to be working better now but still not what I was hoping it would do. I think I'm up to 2-3 gallons of permeate per hour but I can't get a 50/50 split, its more like 25/75. I suspect the issue is running in parallel as many of you mentioned so I'll try and run them in series. My housing has 3/8 inlet at the top and two 1/4 outlets at the bottom. Should I find a fitting that goes from 1/4 to 3/8 so I can keep the 3/8 tubing to the second membrane?

    Thanks for all the help so far.
    2017 - 45 taps on buckets 260gal sap 6gal syrup
    2018 - 92 taps on bags

    All boiled on a homemade 2x5 fuel oil evaporator using 6 steam pans

  10. #10
    Join Date
    Feb 2017
    Location
    NY
    Posts
    51

    Default

    Quote Originally Posted by GoldyCon View Post
    Sorry guys! I got locked out of my account and got busy with COVID issues.

    Attachment 21312

    There is an image of my set up. The system seems to be working better now but still not what I was hoping it would do. I think I'm up to 2-3 gallons of permeate per hour but I can't get a 50/50 split, its more like 25/75. I suspect the issue is running in parallel as many of you mentioned so I'll try and run them in series. My housing has 3/8 inlet at the top and two 1/4 outlets at the bottom. Should I find a fitting that goes from 1/4 to 3/8 so I can keep the 3/8 tubing to the second membrane?

    Thanks for all the help so far.
    Before changing from parallel I would figure out why you can’t get a 50/50 split. You should be able to completely stop the flow of concentrate with the needle valve. That is how you build up more pressure and force more permeate out.


    Sent from my iPhone using Tapatalk

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