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Thread: TDS and nitrates

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    Default TDS and nitrates

    Hi everyone
    I am slightly confused here and hope that someone here can provide me some clarifications.
    I understand Tds is the measure of dissolved solids in water. Like mg ions, sulphates carbonates etc
    But is nitrates also part of this value? Eg TDS measures 150. API test kit nitrate shows 80 for example. Can I assume that 70 is the remaining for the rest of the stuff?

    Thanks

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    Default Re: TDS and nitrates

    Anyone?

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    Default Re: TDS and nitrates

    I think someone will eventually replay. The TDS in of itself is not an issue if the Ph, ammonia, nitrates and nitrites are acceptable. My tanks often run at over 900 TDS without issue or harshi8p on the fish. I would say to mind the ph, ammonia and the two ns and change water often.

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    Default Re: TDS and nitrates

    I did a little googling and

    TDS - "Dissolved solids" refer to any minerals, salts, metals, cations or anions dissolved in water. Total dissolved solids (TDS) comprise inorganic salts (principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides, and sulfates) and some small amounts of organic matter that are dissolved in water."

    TDS consists of major cations and anions (including nitrate).

    In my experience TDS consists of kH and gH and this is what I care about. kH is your buffering for pH and gH is the mineral content of the water. Are you hoping the TDS increases when the nitrate increases? and perhaps indicates a water changes is needed?
    Pat
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    Default Re: TDS and nitrates

    Quote Originally Posted by peewee1 View Post
    I think someone will eventually replay. The TDS in of itself is not an issue if the Ph, ammonia, nitrates and nitrites are acceptable. My tanks often run at over 900 TDS without issue or harshi8p on the fish. I would say to mind the ph, ammonia and the two ns and change water often.
    Thanks Peewee! Yup. I understand about keeping ph ammonia nitrites and nitrates properly. I was just thinking that day about it suddenly and I could not find some really obvious answer on google. Hence the question. ��

    I did even notice spamming dechlorinator bumps up TDS quite a bit. Hence you are right. High TdS may not mean anything too bad.
    Last edited by Jeffkhng; 10-30-2020 at 10:29 AM.

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    Default Re: TDS and nitrates

    Quote Originally Posted by Second Hand Pat View Post
    I did a little googling and

    TDS - "Dissolved solids" refer to any minerals, salts, metals, cations or anions dissolved in water. Total dissolved solids (TDS) comprise inorganic salts (principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides, and sulfates) and some small amounts of organic matter that are dissolved in water."

    TDS consists of major cations and anions (including nitrate).

    In my experience TDS consists of kH and gH and this is what I care about. kH is your buffering for pH and gH is the mineral content of the water. Are you hoping the TDS increases when the nitrate increases? and perhaps indicates a water changes is needed?
    Pat
    Hi pat!
    Your right! I was hoping that the increase in TDS over a week assuming all else stays constant would be nitrate increasing. It’s so much easier to stick a tds pen then to run the api nitrate test!
    I have tried tracking tds over a week and seem to observe that nitrate values raise in similar values. Hence wanted to hear what you people have to say about this!

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    Default Re: TDS and nitrates

    Quote Originally Posted by Jeffkhng View Post
    Hi everyone
    I am slightly confused here and hope that someone here can provide me some clarifications.
    I understand Tds is the measure of dissolved solids in water. Like mg ions, sulphates carbonates etc
    But is nitrates also part of this value? Eg TDS measures 150. API test kit nitrate shows 80 for example. Can I assume that 70 is the remaining for the rest of the stuff?

    Thanks
    The simple answer is yes, nitrates constitute part of the TDS value, but with qualifications. TDS includes both ions which you listed as well as non-ionic dissolved atoms and molecules, such as glucose. The handheld TDS meters measure only electrical conductivity which is due to the number of ions dissolved in the solution (i.e. saline has a high EC/TDS vs fresh water). Even distilled water has a positive but false TDS value if exposed to air due to dissolved CO2 (a dissolved gas not solid). The meter then estimates the TDS from the EC.
    Why are you asking? The safest way to know what your nitrate level is is to measure. But, you can use TDS to estimate nitrates once you have measured both several times in order to establish your correlation values given your water source. It would be worth rechecking periodically to validate your specific correlation values. Also depending on how long you go between water changes your measured EC will underestimate TDS due to increasing non-ionic organic molecules as well as ionic (an amino acid is much larger than a Cl ion but both have the same EC value)
    FYI,Hanna will soon release a freshwater nitrate checker with digital readout for which I will be extremely grateful as I hate judging shades of color.

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    Default Re: TDS and nitrates

    Quote Originally Posted by Jeffkhng View Post
    Thanks Peewee! Yup. I understand about keeping ph ammonia nitrites and nitrates properly. I was just thinking that day about it suddenly and I could not find some really obvious answer on google. Hence the question. ��

    I did even notice spamming dechlorinator bumps up TDS quite a bit. Hence you are right. High TdS may not mean anything too bad.
    I do not know why it occurs but occasionally after working the TDS back down from 900 with daily water changes after a few weeks I can get it to the 200 range then a day or two later it shoots back to 900 again. Almost over night. The fish do not mind it and carry on eating normal, fighting, and spawning.

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    Default Re: TDS and nitrates

    Quote Originally Posted by dspeers View Post
    The simple answer is yes, nitrates constitute part of the TDS value, but with qualifications. TDS includes both ions which you listed as well as non-ionic dissolved atoms and molecules, such as glucose. The handheld TDS meters measure only electrical conductivity which is due to the number of ions dissolved in the solution (i.e. saline has a high EC/TDS vs fresh water). Even distilled water has a positive but false TDS value if exposed to air due to dissolved CO2 (a dissolved gas not solid). The meter then estimates the TDS from the EC.
    Why are you asking? The safest way to know what your nitrate level is is to measure. But, you can use TDS to estimate nitrates once you have measured both several times in order to establish your correlation values given your water source. It would be worth rechecking periodically to validate your specific correlation values. Also depending on how long you go between water changes your measured EC will underestimate TDS due to increasing non-ionic organic molecules as well as ionic (an amino acid is much larger than a Cl ion but both have the same EC value)
    FYI,Hanna will soon release a freshwater nitrate checker with digital readout for which I will be extremely grateful as I hate judging shades of color.
    Hi Don!
    Superb answer. I’ll have to read it a couple times more to really understand you. But I think I get you. Yes I still do my regular water changes. However it is much easier to use the TDS meter. But as you say. The relationship gets more inaccurate with longer time in between. I get it!
    Thanks for much for writing the long paragraph!

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    Default Re: TDS and nitrates

    Quote Originally Posted by peewee1 View Post
    I do not know why it occurs but occasionally after working the TDS back down from 900 with daily water changes after a few weeks I can get it to the 200 range then a day or two later it shoots back to 900 again. Almost over night. The fish do not mind it and carry on eating normal, fighting, and spawning.
    I do also encounter this once in a while. However I do notice that it is typically always when I really muck around with the sand at the bottom kicking up a real mess. Maybe it’s related.

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    Default Re: TDS and nitrates

    Just used nitrates test on my rift lake cichlids came out 0,tested discus tank also O NOW I WONDER IF up to date api test kit is right. I will get a hanna nitrate tester when it comes out.

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    Default Re: TDS and nitrates

    Quote Originally Posted by gunnerschh2 View Post
    Just used nitrates test on my rift lake cichlids came out 0,tested discus tank also O NOW I WONDER IF up to date api test kit is right. I will get a hanna nitrate tester when it comes out.
    Wow! That’s super. Pray your test kit is working alright! I can only get Low nitrates

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    Default Re: TDS and nitrates

    Gunner did you shake the heck out of the second bottle? And the vial after mixing? Second bottle needs some heavy shaking!

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    Default Re: TDS and nitrates

    Quote Originally Posted by Iminit View Post
    Gunner did you shake the heck out of the second bottle? And the vial after mixing? Second bottle needs some heavy shaking!
    Shook like crazy & on api 5.0 & on sea chem kit 5.o. First test was was 2 days after 80 persent water change today was a day before same water change. This was on 450g rift tank that is over stocked because of uncontrollable breeding. Both colors of 2 tests are so hard to read as others have said so come on hana meter. Tom Gunner was the name of my last great German German Shepherd. LOL

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    Default Re: TDS and nitrates

    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.

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