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Thread: Is 30-40 TDS good enough?

  1. #17
    mcantrell's Avatar
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    This one:
    http://www.watermakermini.com/products/index.html

    I got it on ebay at a huge discount.

    For the new price, I'd probably rather get a nice under the sink kit.

  2. #18
    OMG h8 pings MrFlyTrap2's Avatar
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    For a new system, you should be able to get it lower than that, 8 to 0. If it's already doing 30, it's okay but personally I'd like to see it be lower. My RO filter is now running at 30 and the main membrane is over 2 years old now.

    The plants will be happy with 30, but just saying the system should be 8 or less out of the box once the filters have been flushed.
    My Grow List

    "It is only by studying nature that can we ever hope to defeat it."

  3. #19
    Av8tor1's Avatar
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    Most TFC RO membranes are deisgned to have a rejection ratio of 95-99%. As an example, if your inlet to the membrane is 100ppm its outlet would be 1-5ppm. If your inlet was 1000ppm then the expected outlet would be 10-50ppm.

    Of course this is highly dependent on water temperature and pressure differential across the membrane.

    As a rule of thumb, any rejection ratio less then 90% is an indication something is wrong. Before a determination can be made that the membrane is at fault the inlet pressure, water temperature and brine rate must be measured.

    It appears yours is running close to 90%. But with your filter's compact design it may use what is called a CTA membrane. These are resistant to chlorine but are a little less effective with a common rejection ratio of 83-95%.

    On a "typical" system carbon block prefilters are used to remove the chlorine prior to entering the TFC membrane.

    To remove what the membrane doesn't, demineralization by ionization is used with a mixed bed media (commonly referred to as "DI" )

    Example system:



    blue = permeate
    blk = prefiltered water
    yellow = brine
    red = fresh water inlet
    white = bladder tank
    clear = system inlet and outlets


    HTH's
    Av

  4. #20
    OMG h8 pings MrFlyTrap2's Avatar
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    Sorry to hijack this post, but AV have you done any before and after comparison with that pump H? I also bought one of those, and found that it was only wasting a zillion gallons of water. At times I fill up a koi tank with my RO brine water, and when I had the pump it would fill up almost the entire 50 gallon tank. (Maybe 40 gallons?) in one draining of the bladder tank. I decided to remove the pump since I have commercial building pressure, and the koi tank will only fill up about 2 - 4", (sorry can't guess how many gallons that is) during each fillling.

    Maybe it was the extra pressure that was causing all the problems though, but it's just sitting in a drawer now.

    -Nate
    My Grow List

    "It is only by studying nature that can we ever hope to defeat it."

  5. #21
    Av8tor1's Avatar
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    Nate, is yours a permeate pump?.... it should only have isolated the membrane outlet from building up over 5psi back pressure on the membrane.

    To be honest, I love mine... efficiencies went way up, water usage went down and prefilter life went way up

    They are only useful with systems that use the air tank though... as the air tanks fills with water the back pressure on the membrane outlets goes up and up. This increase in back pressure results in a decrease in pressure differentail across the membrane. This results in a proportional drop in rejection ratio, commonly known as "creep". Also the brine rate goes up proportionally as well, wasting water.

    Can you verify what type of pump it is?
    It seems like you are referring to a booster pump which is totally different, has a different purpose and would be plumbed totally different.

    Permeate pumps do not build up additional pressure, they only isolate




    Butch

  6. #22
    Av8tor1's Avatar
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    Nate,

    After reading your post again, it seems as though it was hooked up incorrectly and/or faulty. To increase the brine rate it either A) restricted the outlet of the membrane resulting in a reduction in pressure differential or B) restricted the membrane inlet which resulted in a reduction in pressure differential.

    Can you verify how it was plumbed into the system please.
    Av

  7. #23
    mcantrell's Avatar
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    So, I had a thought. If I'm pumping 30 TDS water into my pots, and thus the water in the tray is 30TDS... after said water evaporates and I pour more water in... won't the water in the tray be higher than 30TDS?

    In short, do I need to wash out my trays every so often?

  8. #24
    Tony Paroubek's Avatar
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    Quote Originally Posted by mcantrell View Post
    So, I had a thought. If I'm pumping 30 TDS water into my pots, and thus the water in the tray is 30TDS... after said water evaporates and I pour more water in... won't the water in the tray be higher than 30TDS?

    In short, do I need to wash out my trays every so often?
    Yes.

    Basically if your water is 30 tds and then half the water evaporates your tds doubles to 60. etc etc etc every time half the water evaporates the tds doubles. Sooner or later the tds will increase to the point where minerals will begin to precipitate and encrust the trays, bottoms of the pots etc.

    If the plants are in contact with the water then it poses potential future problems as the minerals continue to build up. This pretty much goes for anyone that is watering into a closed system where the water can not escape into the ground.
    Is that a Nepenthes in your pocket or you just happy to see me?

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