RO top affect on ph

Discussion in 'Water Parameters and Additives' started by Mc, 22 Jul 2011.

  1. Mc

    Mc

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    Hi all

    Just wondering if anyone can clear something up for me.

    As I understand when RO water has a very low alkalinity I have tested this.
    Because of this when the RO water is store for a while even a few days the pH drops quite alot I tested some water a few days ago and the pH was 6.0.
    If you use this water to top up with what would the effect be?

    I have tried to test after a top and the pH seems ok around 8.0.
     
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  3. Tobes

    Tobes Retired Moderator

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    If you topup gradually and slowly in small quantities or even better with a auto top up unit, then no problem. As long as you pH stays between 7.8 and 8.4 and does not fluctuate. Here are a few articles about low and high pH, etc, maybe you can find something there.

    A Comparison of pH Calibration Buffers by Randy Holmes-Farley - Reefkeeping.com

    A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com

    High pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com

    Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com
     
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  4. leslie hempel

    leslie hempel Moderator MASA Contributor

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    good info provided there tobes,

    my understanding of the RO process is that the water is stripped of all elements and will need to be rebuffered prior to use, i would think that this is most likely why it is suggested that kalk be added to it prior to entering the tank..

    but as tobes says small amounts added a little at a time will be fine and not effect the overall ph ..
     
  5. Mc

    Mc Thread Starter

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    Thanks

    Will read through the links you posted.
    I think that red sea coral pro salt does most of that its just top ups that I've been worried about. Im thinking I might just build an auto top off.
     
  6. lIghty

    lIghty

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    RO basically has no buffer ability, there for the ph you are testing is basically false. If you added only a few drop of vinegar you would notice the ph drop quite a bit, same if you had to add something with a higher ph, this is because there is no/little buffeting ability.

    You can add it to your tank and you would notice no/little chance to the tank ph, but what will happen it will cause your Alk to drop (which could cause a small ph change) this is since you still only have the same amount buffering but in a larger quantity of water, hence it is always a good reason to add a buffer before you dose, as Les stated.
     
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  7. Mc

    Mc Thread Starter

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    Wow thanks

    Now thats very interesting, that clears things up alot.
     
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