Salinity dropping

Discussion in 'General Discussions and Advice' started by Zandy, 29 Jun 2013.

  1. Zandy

    Zandy

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    Just want to know if anybody have a an idea as to what could possible cause a constant drop of salinity. The water tested after mixing and before adding into the tank reads 1026, measured with a calibrated refractometer. I have measured it with another refractometer and gets the same reading. After about 24hrs the salinity drop to 1020. I raise it again, but it keeps dropping. This has me stunned. I have looked for salty creep and have found none...any ideas ???
     
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  3. Andre@ReefAquatics

    Andre@ReefAquatics Sponsor

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    ATC - Automatic Temperature Compensation.

    Make sure your Refrac's compensate for changes in Temp as SG varies with temperatures.

    But what you saying is kinda weird, that you are adding and its still dropping ?
     
    Last edited: 29 Jun 2013
  4. Zandy

    Zandy Thread Starter

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    Andre' could you please explain what you mean ? I make sure my water is on temp at 1026 at 25deg before adding to the tank. Does a refractometer take temprature in consideration? I understand that it could be like that with a hydrometer.But not understanding the temprature as it could not from my understanding affect the refractometer.
     
  5. butcherman

    butcherman Moderator MASA Contributor

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    Out of curiousity what does your tank read with the same refratometer? Sometimes the refractometer can be De-calibrated with a slight bump.
     
  6. Zandy

    Zandy Thread Starter

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    @butcherman i re-calibrated the refractometer again to read 0 against my Ro water (RO water TDS 0.002) i then tested it on another tank and salinity reads 1025. Tested on another tank of mine and also salinty reads 1025. Put it back into the tank with low salinty and gets reading 1022 (started raising it slowly). Also used a floating hydrometer and giving me the same reading as refractometer. Temperature on the 3 different tanks as follows: Tank 1 - Salinty 1025 - Temp 25.5 Tank 2 - Salinity 1025 - Temp 27 Tank 3 - Salinity 1022(used to be 1020) - Temp 27
     
    Last edited by a moderator: 26 Nov 2015
  7. mala1610

    mala1610

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    Dip the refractometers tip part in your tank for 15min it must be at your tanks temp ... If you have a small bottle of RI liquid do the same ... Then check
     
  8. carlosdeandrade

    carlosdeandrade

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    You need to get your refractometer to the same temp as your tank after its been calibrated from a water supply that has a known salinity. For example, take it to a LFS with refractometers or preferably a hydrometer. They will then calibrate your refractometer to their hydrometer or their calibrated refractometer.
    Do not use RO water to calibrate as this is incorrect as salinity refractometers are only meant to read salt water.
     
  9. mala1610

    mala1610

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    I agree don't use RO
    Even better try get hold of some or buy some RI liquid by the time you get back with your calibrated refractometer it could be out.
     
  10. Smirre

    Smirre

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    Hmmm sal More kom Toesig gee;)
     
  11. Visser

    Visser MASA Contributor

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    What is the volume of the tank? How much topup water do you normally use / day & is it still the same?
     
  12. Zandy

    Zandy Thread Starter

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    @carlosdeadrade thanks i will go to Wild on Pets tomorrow and let them check. Just weird that i get the same reading with a floating hydrometer. I never got RI liquid with my refractometer but will get some. Thanks all for the input !!!
     
    Last edited by a moderator: 26 Nov 2015
  13. Zandy

    Zandy Thread Starter

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    Tank is 780 liter and using around 10l top up a day. The top up is unchanged and still the same. That was the first place i started looking
     
  14. Nemos Janitor

    Nemos Janitor

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    The temperature of the sample water is irrelevant. The small sample will quickly equate to the temperature of the testing instrument.

    Through the viewer of the refractometer you will se a calibration indication. Something like 20/20. This is the temperature the INSTRUMENT should be calibrated at. You can use RO water at any temp to calibrate the refractometer as long as the instrument is at the calibration temperature.


    Not sure what this will achieve other than submit the instrument to possible water damage.

    Not true with ATC refractometers. In fact with non ATC refractometers as well. Refractometers measure SG specific gravity at a calibrated temperature. The instrument temperature determans the SG reading at the calibrated temp or in the case of a non ATC refractometer.

    The first aquarium salinity refractometr D-D salt water refractometer works perficaly by calibrating with RO water.



    To get back to the salinity drop issue. What salt are you using?
     
  15. carlosdeandrade

    carlosdeandrade

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  16. Zandy

    Zandy Thread Starter

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    I am using an ATC refractometer. I am using seachem reef salt. I bring the salinity up in the tank to 1025 just for it to drop in about 3 hours back around 1022 . I have tested the water with a floating hydrometer as mentioned above and get the same reading via that ?? Yet with the same refractometer i get correct readings on my other tanks
     
  17. LCornelius

    LCornelius Moderator

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    I agree with uncle nemo!

    This is not a issue with your refractometer!

    How do you mix your salt?
    Please explain the steps and time frame.
     
  18. Nemos Janitor

    Nemos Janitor

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  19. carlosdeandrade

    carlosdeandrade

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    Dipping your refractometer tip into v water won't damage it, only if you submerge the whole thing. Water is placed on it anyway. Also don't understand your statement "not true with ATC refractometers. In fact with non ATC refractometers as well."
     
  20. Nemos Janitor

    Nemos Janitor

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    Zandy what happens to the KH and ca readings do they drop as well?
     
    Last edited: 29 Jun 2013
  21. Zandy

    Zandy Thread Starter

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    Ok the mixing is done this way

    RO water is made in the morning in a seperate drum (used only for RO) then measured to make sure the TDS is correct (currently 002) then i weigh the Seachem Reefsalt in a digital scale to the mixing instructions... I add my RO water to the seawater drum and bring the water up to temp 25deg. I then add my salt to the RO and let the powerhead mix it for around 2hrs. It's then used. I never let the water stand for more than 24hrs.
     
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