Is there something better than mixed bed DI resin? | BRStv Investigates

Discussion in 'Reef Aquarium Discussion' started by randyBRS, Oct 13, 2017.

  1. Adsjj

    Adsjj Member

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    Na no siporax at all. made sure I didn't have any signs of that in my tank. I have given the tank 100 litre water change over 2 days cleaning 60% of the sand as I had elevated sulphur and had noticed a few black patches of sand in some calm areas at the back so have remove this and given it a good clean in fresh RO water. new pod arrived so now have 4 stages on RO unit. goes Cation 7tds, Anion 1 tds, Mixed Bed 0 tds, Mixed Bed 0 tds, I would hope now I am removing a lot of the silicate from the RO water. fingers crossed. thanks for all you help and info though guys.
     

  2. Felipebarile

    Felipebarile New Member

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    Hi doctor, accompanying some forums here from my country, I saw that some people have stopped using resins and are using Gfo (granular ferric oxide) and say they have not had any more problems with phosphate and silica and report that it lasts longer than the resins. Do you find this exchange interesting?
     
  3. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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    That's a fine way to remove phosphate and silicate, but what about issues such as copper?
     
  4. Felipebarile

    Felipebarile New Member

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    I understood and I did not even remember that the tap water can come with even excess copper. so you better not take the risk.

    Another question is in relation to a great configuration for the DI filter. I want to leave my water with excellent quality and I wanted your suggestion of which sequence of resins best suited to have this water with good quality and quantity.

    I thought of:
    option 1: 600gr cationic > 600gr anionic > 600gr mixed

    I was also suggested:
    anionic> mixed> mixed
     
  5. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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    Both of those will make perfect water. There can be debate over what costs least, and that answer will vary with the nature of the water you use and how much CO2 may be in it (and what ratio is even in a mixed bed).
     
  6. Felipebarile

    Felipebarile New Member

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    What is the amount of CO2 that would be ideal or closer to the ideal?

    if the value is lower than expected how would you place the resins? and if it is above ideal how would it look? or has no relationship?
     
  7. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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    Zero CO2 is ideal. Any CO2 passes through an RO pretty easily and depletes the anion binding DI resin
     
  8. yellrihs

    yellrihs Active Member

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    Looking for an answer to this question, however my TDS after the membrane is 8 then jumps to 35 TDS after the Anion and then 0 TDS after the 3rd stage mixed purple. Is it normal for the TDS to increase after the Anion?
     
  9. Ryanbrs

    Ryanbrs Well-Known Member R2R Supporter Platinum Sponsor

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    There no use in measuring tds after the just anion because it hasn’t removed anything. The resin has just exchanged negatively charged contaminants for hydroxides which many very well have a stronger electrical charge than whatever was in the water. Remember the tds meter isn’t really reading tds it’s estimating them by measuring the electrical charge of the water.

    It’s only valuable to measure tds after both cation and anion stages or a mixed bed where the hydroxides and hydrogen from both resins have formed pure water.
     
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  10. yellrihs

    yellrihs Active Member

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    Thank you!
     
  11. balkin

    balkin Member

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    So does everyone here leave the RO/DI system under pressure? That is do you leave the water on to the system all the time?? I turn mine on and off as needed, does this cause any issues??
     
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  12. randyBRS

    randyBRS BRStv Host :-) R2R Supporter Gold Sponsor

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    I'd say that it really doesn't matter either way. Here at BRS our systems are always pressurized, while at home (since I was using the faucet diverter and not a direct connection to the water line) I turned the water off after making what I needed. :)
     
  13. chipmunkofdoom2

    chipmunkofdoom2 Always Making Something R2R Supporter R2R Excellence Award Reef Squad Article Contributor

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    The pressure is not really that important, but keeping the membrane wet is. Drying out a TFC membrane after it has been used will ruin it. If you can prevent the water from draining out of the system when you depressurize it, then you don't need to keep your system pressurized. However, it's difficult to ensure that the membrane remains 100% submerged if you shut off the source water and don't block the output line(s). Leaving the system pressurized is a good way to ensure the membrane stays wet.
     
  14. balkin

    balkin Member

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    Thank you!
     
  15. balkin

    balkin Member

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    That makes a lot of sense!!
     
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