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Thread: TDS and nitrates

  1. #16
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    Default Re: TDS and nitrates

    Quote Originally Posted by dspeers View Post
    Can't believe the nitrates are zero. The TDS jump is also a puzzle, although if the gH is high or there are other salts in the tank with relatively low solubility then messing around with the substrate will jump up the TDS. My understanding of the Hanna Nitrate checker was on the basis of a phone conversation I had with one of the company reps. But, I checked their website today and they recently released a low level (0-5) marine Nitrate checker, so I hope I did not misunderstand. Will be really upset as I love digital readouts and flat out hate trying to accurately judge color wheels. Sent them an e-mail and will update with their answer.
    Just recalled a discussion with coralbandit in re using TDS as a water quality indicator. He has had great success and if you have ever looked at his ram breeding you will agree. Cannot recall the thread but you could pm him for feedback. By the way did not mean to suggest that TDS is not a good value to follow and is certainly easier to determine than nitrates, just that it is a little more nuanced than increased TDS = increased nitrates.
    The substrate idea was just a guess. I can’t verify that actually. You are right that for that to be happening maybe there’s undissolved salts sitting there. Seems unlikely though. ��

    Thanks for all the replies. Much to learn!

  2. #17
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    Don Speers

    Default Re: TDS and nitrates

    What else could it be? Remember the TDS is really an EC value which directly correlates to the # of free ions in solution. An almost immediate jump from 200 to 900 is hard to explain any other way.
    Did make a misstatement earlier, indicated that an amino acid had the same effect per ion as an inorganic acid, similar value but not the same, pKa, temperature, and molecular size all play and each ion has a different EC vs concentration curve, and a different EC vs temp curve.

  3. #18
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    Default Re: TDS and nitrates

    Quote Originally Posted by dspeers View Post
    What else could it be? Remember the TDS is really an EC value which directly correlates to the # of free ions in solution. An almost immediate jump from 200 to 900 is hard to explain any other way.
    Did make a misstatement earlier, indicated that an amino acid had the same effect per ion as an inorganic acid, similar value but not the same, pKa, temperature, and molecular size all play and each ion has a different EC vs concentration curve, and a different EC vs temp curve.
    Hi Don. Don’t get me wrong. I don’t know these chemistry stuff too well myself. I just meant that substrates in the tank so how could it be undissolved if it’s already underwater. From a lay man point of view. You could very well Be right! Btw the tds example of 200 to 900 is actually someone else’s situation.
    Cheers!

  4. #19
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    Don Speers

    Default Re: TDS and nitrates

    Frankly, I am kinda guessing here but in a non-turbulent setting (as in the water below the top of substrate) you will get a gradient where there is a somewhat higher concentration of heavier substances, with subsequent precipitation of less soluble salts even underwater (that's why some older aquariums show lime stains below the water line). Stir it up and they return to solution. If that's not what's happening, I am at a complete loss as to what would kick up the TDS. Frankly, I am no chemist, just recalling what I learned as part of pre-med requirements. I get that your numbers are not the same as Peewee's, his are a puzzle. What are your #s pre and post substrate cleaning?

    Anyone else have an idea what would cause such a big change in TDS over a short time frame?

  5. #20
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    Default Re: TDS and nitrates

    A TDS of 900 surely cannot be right ???

  6. #21
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    Default Re: TDS and nitrates

    A TDS of 900 surely cannot be right @Peewee ???

  7. #22
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    Default Re: TDS and nitrates

    Quote Originally Posted by eros111 View Post
    A TDS of 900 surely cannot be right ???
    I get readings of 950 several times. Beginning at around 250 for several weeks it shoots up to over 900 TDS in one day. As I continue to make daily water changes each day the TDS will drop by 50 or more. Such as 950 then mid 800s then 600s until eventually back to the high 100s to low 200s where it will remain for a time. Then suddenly back to over 900. The water is clear and the fish do not notice it. Like I said the continue to go about their business of eating, chasing around, and preparing for spawning.

  8. #23
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    Default Re: TDS and nitrates

    If I were getting these readings I would get a second TDS meter, fairly cheap. If both read the same I would be at a complete loss.

  9. #24
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    Default Re: TDS and nitrates

    Quote Originally Posted by dspeers View Post
    If I were getting these readings I would get a second TDS meter, fairly cheap. If both read the same I would be at a complete loss.
    I suppose there could be such a thing as a faulty meter. I will look for one to buy.

  10. #25
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    Default Re: TDS and nitrates

    You know this is so bizarre, I would start checking my source of water prior to adding to tank. Google Hanna Primo TDS tester.

  11. #26
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    Default Re: TDS and nitrates

    Ignoring the rare times I get the results from stirring the substrate. I only get huge jumps if I dump salt or dechlorinator.

  12. #27
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    Default Re: TDS and nitrates

    Quote Originally Posted by Jeffkhng View Post
    Ignoring the rare times I get the results from stirring the substrate. I only get huge jumps if I dump salt or dechlorinator.
    This jump to 900 did follow a treatment of Prazzipro and salt. That could be the contributing factors.

  13. #28
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    Default Re: TDS and nitrates

    I agree, i think the salt could be it. Sea water has about 50X electrical conductivity and therefore TDS of average tap water.

  14. #29
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    Don Speers

    Default Re: TDS and nitrates

    You can skip getting a second TDS meter.

  15. #30
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    Default Re: TDS and nitrates

    Quote Originally Posted by peewee1 View Post
    This jump to 900 did follow a treatment of Prazzipro and salt. That could be the contributing factors.
    It’s definitely the salt! You can even hit the thousands! Try dumping salt in to bucket and measure before and after! I never knew my handheld pen could read into thousands!

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