'by The Numbers..' Help With Ro System Please?

Discussion in 'Water Fed Pole Cleaning' started by Kips, Jul 28, 2013.

Advertisement
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Welcome to the UK Window Cleaning Forums.
    Starting or own a window cleaning business? We're a network of window cleaners sharing advice, tips & experience. Rounds for sale & more. Join us today!

  1. Kips

    Kips Well-Known Member
    Member

    Joined:
    Jun 19, 2012
    Messages:
    589
    Likes Received:
    94
    Hey folks.

    I have a little 50gpd RO system i've set up in my house, just for filling barrels and etc. I've been doing some number crunching with it, and I think something may be wrong!

    I timed how long it took to produce a litre of pure water. Pretty much 20 minutes, on the nose.

    So, that means it's producting 5 litres per hour of pure water. So 5 hours for a 25 L drum..

    I also measured the waste water. It was about 6 litres, rounding down a little bit. So that's producing 30L of waste water per hour, meaning about 150L of waste water for 25L of pure water. Working out percentages, I come up with 16% (ish) pure water, 84% (ish) waste water.
    Do these numbers sound right? Seems like a very slow, and wasteful way to get pure water.. 5 hours for a 25 litre drum? if I wanted to go out with say 250L of water, then - I'd need to fill for 50 hours? And I'd waste 1,500 Litres of water??!!


    What the....???!!!!!
     
    Advertisement
  2. Tuffers

    Tuffers Hero
    Member

    Joined:
    Sep 10, 2012
    Messages:
    9,386
    Likes Received:
    2,742
    1L x 20 minutes = 3L per hour surely.
     
  3. OoO

    OoO Guest

    PPM before and PPM after?
     
  4. spruce

    spruce Grand Master
    Member

    Joined:
    Jun 4, 2012
    Messages:
    2,536
    Likes Received:
    736
    As Tuffers has suggested, your pure figures are incorrect. I would also guess that the waste figure is also suspect.

    I don't know what system you have, but the usual way of 'throttling' the waste is with a 3 to 1 inline restrictor which is what we had. You need to restrict the waste so that you get a 3 litre waste output to 1 litre of pure. Remember your 50GPD r/o is optimum (water temperature and water pressure) over a 24 hour period. They are also American gallons which aren't the same as imperial gallons (smaller).

    Once you get the waste to pure ratio right, you will produce more pure provided you have a decent water pressure.

    IMHO a 50GPD r/o is a complete waste of time for window cleaning. In the winter it will produce 1/2 of what it is now with the colder tap water temperatures.

    Daqua are advertising a 300GPD unit at a very good price - the 450GPD is only £20.00 more which I would recommend. Process into an IBC tank and use a submersible to fill your containers/tank. You would just need to connect a water timer to the supply tap for it to switch off in X number of hours.
     
  5. Richard Hyde

    Richard Hyde Member
    Member

    Joined:
    Jun 23, 2013
    Messages:
    61
    Likes Received:
    5
    i use a bigger system and get 100 litres of pure water every 4 hours ,, suspect your water pressure coud do with bein raised ???
     
  6. Kips

    Kips Well-Known Member
    Member

    Joined:
    Jun 19, 2012
    Messages:
    589
    Likes Received:
    94
    Yeah, it's only 40PSI, I have been looking into a booster pump but we have a 'proper' system on the van, I was just setting this one up half out of boredom and half so we have a backup and can do work with backpacks if anything ever happens to the van etc as a short term fix.

    Ok so, as someone pointed out, my figures are ****, way out. I will redo them but not now as I'm tired and i'm having a beer as I have tomorrow off!

    Has anyone seen those 'low pressure' RO filters, are they any good? If I spend 30 quid on a 150gpd one, will that make the difference? since it is designed to work at my houses PSI?


    Basically can someone wise tell me how to fix it, I am not skilled when it comes to these matters... lol

    Buying a new RO system would of course fix it, but I want to spend the least amount possible, remember this is only for backup, for filling a few barrels if the need arises etc. If I could filter about 250L a day without using up half an ocean i'd be happy.
     
  7. spruce

    spruce Grand Master
    Member

    Joined:
    Jun 4, 2012
    Messages:
    2,536
    Likes Received:
    736
    That 150 GPD membrane will go into your housing. Get an inline resistor and you will be up and away. We used a 450GPD r/o on 40/50 psi for years without a booster pump. Yes, water production wasn't as fast, but as a backup spending money on booster pumps is probably going too far. Our water TDS was 255 and pure was 4/5 ppm. After all mains were relined, our tap tds dropped to 115 and our r/o was producing pure at 2ppm.
     
  8. wilgold

    wilgold Active Member
    Member

    Joined:
    Nov 30, 2011
    Messages:
    132
    Likes Received:
    4
    Kips I was in a similar situation as you however my original system was a 100gpd.

    I've just found these photos that i took whilst upgrading my system last summer. It kinda gives you an idea of the difference between systems and using a booster pump.


    Original 100gpd system

    ImageUploadedByTapatalk1375126898.622309.jpg

    Original 100gpd with booster

    ImageUploadedByTapatalk1375126943.021912.jpg

    Upgraded to 200gpd

    ImageUploadedByTapatalk1375126983.588806.jpg

    200gpd with booster

    ImageUploadedByTapatalk1375127010.588439.jpg

    Each photo was taken over 20mins. Waste is on the left and pure is on the right.

    Hope it uploads ok using my iphone!
     
  9. Kips

    Kips Well-Known Member
    Member

    Joined:
    Jun 19, 2012
    Messages:
    589
    Likes Received:
    94
    So with the 200gpd and booster you were getting more pure water than waste water? Or is it pure on the left and waste on the right?
     
Advertisement