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Thread: Prefilter micron; before or after pressure pump

  1. #1
    Join Date
    Mar 2008
    Location
    Central Ohio
    Posts
    318

    Default Prefilter micron; before or after pressure pump

    Does everyone use 5 micron pre-filters? 5 is too tight for my RO system that relies on gravity feed (no supply pump). Pressure pump gets starved. Manufacturer suggests using 10 or 20 micron, and possibly adding a small supply pump.

    My pre-filter is before the pressure pump--hence the problem it creates by starving the pump. I have seen pre-filters installed after the pressure pump. Is this the most common setup? How much pressure can the pre-filters handle?
    Central Ohio
    Leader WSE 2x6
    Old metal corn crib converted to "The Shack"
    Smoky Lake 6 gallon water jacket canner
    Daryl 5" filter press with air pump
    Deer Run 125 RO

    2023: 140 taps, buckets, 32 gallons
    2019: 100 taps, buckets, 45 gallons
    2018: 100 taps, buckets, 31 gallons
    2017: 100 taps, buckets, 15 gallons
    2015: 100 taps, buckets, 34 gallons
    2014: 100 taps, buckets, 30 gallons
    2013: 100 taps, buckets, 52 gallons

  2. #2
    Join Date
    Jan 2006
    Location
    Oneida NY
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    11,547

    Default

    I've only seen ones with a feed pump. They have the pre-filter after the feed pump and before the pressure pump.
    Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
    Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
    Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
    After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.

  3. #3
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    Mar 2008
    Location
    Central Ohio
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    318

    Default

    Thanks, Dave. Sorry to see the news about your bad hip.
    Central Ohio
    Leader WSE 2x6
    Old metal corn crib converted to "The Shack"
    Smoky Lake 6 gallon water jacket canner
    Daryl 5" filter press with air pump
    Deer Run 125 RO

    2023: 140 taps, buckets, 32 gallons
    2019: 100 taps, buckets, 45 gallons
    2018: 100 taps, buckets, 31 gallons
    2017: 100 taps, buckets, 15 gallons
    2015: 100 taps, buckets, 34 gallons
    2014: 100 taps, buckets, 30 gallons
    2013: 100 taps, buckets, 52 gallons

  4. #4
    Join Date
    Feb 2018
    Location
    Canaan Valley, WV
    Posts
    220

    Default

    I think I am having the same issue with pressure pump being starved. I want to add a low pressure pump, since I want to expand the RO and add another membrane anyway. Does anyone know if this will work well as a low pressure pump?

    https://www.chuggerpumps.com/product/xcpss-in-1-115v/

    thanks!!

  5. #5
    Join Date
    Jan 2010
    Location
    Covington, New York
    Posts
    1,680

    Default

    My RO is a pressure pump only model, with the filter before the pump. I found early on it will only work well with one particular brand of filters, Purtrex. They are the "fuzzier" ones, and not the smoother ones, if that makes any sense. The smoother ones very much starved the pump.
    Noel Good
    1998 to 2009: 15 taps on buckets, scavenged fire pit and pans
    2010: New 2x4 SS flat pan w/preheater
    2015: New to me Lapierre 18x60 raised flue, new shack, new everything!! 59 taps 23.75 gallons
    2016: 85 taps 19 gallons
    2017: Purchased 2.5 acres and tubed half with 3/16. 145 taps total 49.25 gallons
    2018: 200 taps (162 on 3/16ths 38 on buckets) New NextGen RO 63 gallons
    2019: 210 taps 73.5 gallons
    2023: 210 taps 89.75 gallons
    www.wnybass.com

  6. #6
    Join Date
    Mar 2008
    Location
    Central Ohio
    Posts
    318

    Default

    I feel like I'm trying to reinvent the wheel here with my problem as mentioned by others here: Procon pressure pump (approx 4 gpm max with pressure valve wide open) is being starved by gravity feed through pre-filter. Ray at Deer Run says try 10 micron cartridge instead of 5 micron--or maybe use feed pump. Maybe the Purtrex filter cartridges will work. If I go with a feed pump it seems impossible to find one that feeds just over 4 gpm that doesn't rely of oil lube. What do you RO veterans advise for us RO rookies?
    Central Ohio
    Leader WSE 2x6
    Old metal corn crib converted to "The Shack"
    Smoky Lake 6 gallon water jacket canner
    Daryl 5" filter press with air pump
    Deer Run 125 RO

    2023: 140 taps, buckets, 32 gallons
    2019: 100 taps, buckets, 45 gallons
    2018: 100 taps, buckets, 31 gallons
    2017: 100 taps, buckets, 15 gallons
    2015: 100 taps, buckets, 34 gallons
    2014: 100 taps, buckets, 30 gallons
    2013: 100 taps, buckets, 52 gallons

  7. #7
    Join Date
    Jan 2010
    Location
    Covington, New York
    Posts
    1,680

    Default

    Quote Originally Posted by maple marc View Post
    I feel like I'm trying to reinvent the wheel here with my problem as mentioned by others here: Procon pressure pump (approx 4 gpm max with pressure valve wide open) is being starved by gravity feed through pre-filter. Ray at Deer Run says try 10 micron cartridge instead of 5 micron--or maybe use feed pump. Maybe the Purtrex filter cartridges will work. If I go with a feed pump it seems impossible to find one that feeds just over 4 gpm that doesn't rely of oil lube. What do you RO veterans advise for us RO rookies?
    I would definitely give the Purtrex PX05 filter a try first. Anything else and I could visibly see air bubbles in the tubing between the filter and the pump.
    Noel Good
    1998 to 2009: 15 taps on buckets, scavenged fire pit and pans
    2010: New 2x4 SS flat pan w/preheater
    2015: New to me Lapierre 18x60 raised flue, new shack, new everything!! 59 taps 23.75 gallons
    2016: 85 taps 19 gallons
    2017: Purchased 2.5 acres and tubed half with 3/16. 145 taps total 49.25 gallons
    2018: 200 taps (162 on 3/16ths 38 on buckets) New NextGen RO 63 gallons
    2019: 210 taps 73.5 gallons
    2023: 210 taps 89.75 gallons
    www.wnybass.com

  8. #8
    Join Date
    May 2009
    Location
    UVM Proctor Maple Research Center, Underhill Ctr, VT
    Posts
    6,391

    Default

    1. Try 10 micron filters.
    2. Is the line after the filter clear....if so, can you see ANY bubbles? If so, that's the problem. Air leaks on the suction side can cause the pump to shut off.
    3. Is the tank level above the level of the RO? Any amount of head pressure you can get will be helpful.
    4. Put a small bleeder valve in the line at a high point, but close to the RO to make sure you're getting every bit of air out. How long is it running before it shuts off?
    5. If all else fails, try (for a short test) removing the filter cartridge and running it for a little while. That'll help diagnose whether it is air or the restrictions due to the filter or something else causing the problem.
    Dr. Tim Perkins
    UVM Proctor Maple Research Ctr
    http://www.uvm.edu/~pmrc
    https://mapleresearch.org
    Timothy.Perkins@uvm.edu

  9. #9
    Join Date
    Mar 2008
    Location
    Central Ohio
    Posts
    318

    Default

    Thank you for ideas.

    1. I have ordered Purtrex "fuzzy" 5 micron cartridge to try; I also ordered some 10 micron cartridges to try
    2. Hose between filter and pump is clear. With 5 micron cartridge, hose is collapsing and air bubbles are visible. Pump also makes noises and motor gets hot, shuts off.
    3. Feed/drain valves from both permeate and sap totes are several inches above inlet on RO
    4. See 5.
    5. I ran the RO for a little while without the filter cartridge, running sap that had already been through the RO once. Ran perfectly--no bad noises from pump; no collapse of clear hose between filter and pump; no air bubbles in that hose. Much better volume.

    I'm hoping the 10 micron cartridges or the 5 micron Purtrex cartridge can increase flow adequately on gravity. Running the RO without a filter cartridge while doing a permeate rinse doubles the flow through the pump from 2 gpm to 4 gpm.
    Central Ohio
    Leader WSE 2x6
    Old metal corn crib converted to "The Shack"
    Smoky Lake 6 gallon water jacket canner
    Daryl 5" filter press with air pump
    Deer Run 125 RO

    2023: 140 taps, buckets, 32 gallons
    2019: 100 taps, buckets, 45 gallons
    2018: 100 taps, buckets, 31 gallons
    2017: 100 taps, buckets, 15 gallons
    2015: 100 taps, buckets, 34 gallons
    2014: 100 taps, buckets, 30 gallons
    2013: 100 taps, buckets, 52 gallons

  10. #10
    Join Date
    Feb 2017
    Location
    NY
    Posts
    124

    Default

    You could also get a stainless filter housing rated to 300psi and put it after the pressure pump. The prefilter itself should be fine as the pressure differential across the filter would be minimal (it wouldn't collapse).

    Are you using a 10" or 20" filter housing?
    What are your inlet and outlet port sizes? What size hose are you using, and is it an OD connection or is it going into a barb (what size is the ID of the barb?).

    I would use a hose capable of withstanding suction. As soon as that hose collapses the problem is exacerbated.

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