Pure water problems

Discussion in 'Water Fed Pole Cleaning' started by Carlton, Jan 15, 2015.

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  1. Carlton

    Carlton Newcomer
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    Hi Everyone.
    Having a problem with my water purification system which is as follows:

    Typical 3 stage pre filter (5 micron, carbon block, carbon GAC)
    Typical 3 stage RO system which produces 300 litre per day
    20" resin filter using high quality Tulision resin
    This feeds a 1000litre storage tank
    Tape water varies between 175 and 275ppm

    I wouldn't say my system is used heavily, maybe about 1000 litres per week.
    I back flush my system regularly (monthly)
    I been using the pure water system for about 5 years
    I change the pre filters approx. every 6 months.
    Last summer I changed my RO units for the first time.
    Change my resin as and when ppm raises above 12-15ppm

    Problem:

    My water quality has has dropped off a cliff measuring about 50ppm. (4 days ago) So I immediately changed my resin which worked, bringing the reading back to zero. But within 36 hours to was right back up. I have just (today) changed all three pre filters and re-connected the system but without the resin filter. It measures 55ppm (tape water 200ppm). Which seems high, so I have also measured the water quality before the RO section - so just the pre filters - and that measures 200ppm, same as the raw tape water. Indicating to me that the pre-filters are not doing anything.

    So my overall question is - Where does my problem lie?

    Approx. what amount of impurities should the pre filters alone remove?

    Approx. What amount should the RO units remove?

    Approx. What amount should be left for the resin to remove?

    I'm at a loss as to which part or parts of the system are failing and why...

    Thanks to all who read this, hope it's understandable and thanks in advance for any help.

    Regards
    Carlton
     
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  2. Smurf

    Smurf Banned
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    Are you aware of tds creep when you first start up a ro each time?
     
  3. Carlton

    Carlton Newcomer
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    Not sure what TDS creep is.... Could you explain...

    Thanks
     
  4. Smurf

    Smurf Banned
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  5. Carlton

    Carlton Newcomer
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    OK. Thanks for that.

    The tds reading is initially about 80-90ppm then drops to 55-60ppm after a minute or so. but does not drop after that.
     
  6. Smurf

    Smurf Banned
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    I backflush my 300gpd ro every time I go to use it for about 30 mins to prolong the life of the membranes as can get clogged quickly if you don't.

    How old are your membranes as sounds like they are knackered?
     
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  7. Carlton

    Carlton Newcomer
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    I've just been checking up on that, thought it was last summer but it was acually the summer before, so 18 months old. Not sure how long they should last. I bought the unit second hand and didn't need to replace them for the fist 3 years, so thought they would last longer than 18 months. I'm I wrong?

    Seems like you back flush alot more than me. Was always told that every month would be sufficient. Maybe not?

    Who should I view the pre filter figures? Is it normal to see that they do not lower the tds readings?
     
  8. Carlton

    Carlton Newcomer
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  9. spruce

    spruce Grand Master
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    Prefilters won't make much of a difference to the tds of the tap water passing through them.

    The carbon block and GAC filters remove chlorine from the water. Chlorine damages r/o membranes.

    Without knowing what carbon block filter you are using, it becomes difficult to make a helpful suggestion. However GAC filters only have a service life of 2500 US gallons according to the label included in my last order. An American gallon is slightly smaller than our Imperial gallon.

    Using your stats as a guide, you are using around 4000 litres a week to process 1000 liters of pure if your pure to waste ratio is 3 to 1 which most are that have an inline restrictor fitted. If you were using a CAG filter alone then it would need to be replaced every 2 weeks or so.

    A Fiberdyne 10" carbon block filter is good for around 38000 litres. I believe these are the best on the market. At your usage, you would need to replace a Fiberdyne C/B filter every 10 weeks.

    But in the early days I only used GAC filters and our r/o membranes lasted 6 years with a 3 month prefilter replacement cycle. This experience of ours probably shows how the makers recommended filter replacement schedule and our experience can be vastly different - unless they have changed to spec of the GAC filters. (The first r/o I purchased was a year old. It was part of a system being sold by a local lad. He changed the prefilters for the first time just before I bought it. Those membranes lasted me another 6 months and they were shot. Changing prefilters sooner is always recommended.)

    However, there are cleaners on this and other forums who only change their prefilters every 6 months and process much more water than you do. I guess the amount of chlorine added by the water companies is different from area to area.
    One thing I do watch for is when the water companies flush the pipes. I try not to use my r/o at this time.

    I would try to find if you have a rogue membrane. I would disconnect the pure on each membrane housing and test the output with my tds meter. (As per Smurf's post - wait about 10 minutes after you start the r/o to let it settle down.) Test after membrane and before di.

    Years back RoMan told us to only buy quality membranes. They said that the cheap Chinese copies weren't very good. That was 8 years ago so I don't know if the same advise still applies.

    Personally I would only purchase prefilters and membranes from trusted suppliers, Gardiners, Daqua, Gaps Water, RoMan to name a few. Ebay isn't the best place for quality stuff IMHO.
     
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  10. Carlton

    Carlton Newcomer
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    Quite a bit for me to consider there. And thanks spruce & smurf for your imput.

    I did buy my replacement RO units from ebay. £70 for 3. Will look at the suppliers you have recommended this time round.

    I am now going to test the individual membrane's as you suggest.

    Just one last question. Typically what tds reading should I expect after pre filter and RO but before resin?
     
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