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Pottassium Carbonate Confusion

Discussion in 'Aquatic Plant Fertilization' started by Sangeeth Ramanunni, Sep 15, 2017.

  1. Sangeeth Ramanunni

    Sangeeth Ramanunni Junior Poster

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    Kh is 1dkh and Ph is 6 for my well water. So when I increase CO2, the Ph drops drastically and the fishes star to struggle. I have been adviced to raise the KH by adding Pottassium Carbonate. I need help on the following matters.
    1) I am using teaspoons to add ferts. But when I try to calculate the dosage for K2CO3 in rotalabutterfly.com , it shows only gram value, which is 2.94 gm for my 60L tank. Can any one suggest me how to convert it to teaspoon rate?

    2) There is something else in the market name Pottassium carbonate Anhydrate CK2O3. Can this be used to raise KH
     
  2. Christophe

    Christophe Subscriber
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    1) 3 g of K2CO3 is going to be about half a teaspoon so

    2) That's basically the same thing you're already using, just go with what you've got.
     
  3. Sangeeth Ramanunni

    Sangeeth Ramanunni Junior Poster

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  4. Sangeeth Ramanunni

    Sangeeth Ramanunni Junior Poster

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    One more question. WHen I calculated the dose of K2CO3 for raising dKh by 2, I found that it adds 27 ppmof Pottassium. Is this okay?
     
  5. tiger15

    tiger15 Member

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    Being new to planted tank, please correct me if I were wrong. From what I read, potassium is the most benign nutrient that over dosing it has no known toxic effect on fish or plants, and will not induce algae. I am currently dosing 20 ppm of K with K2SO4.

    I have similar concern that optimizing CO2 to 30 ppm may crash my hard water fish as it is necessary to lower the pH below 6.6 in my 4kH tap water. It's good to know that K2CO3 is an alternative source of K as well as a kH booster. So if I use K2CO3 in place of K2SO4, I can inject more CO2 without crashing pH.

    However, K2CO3 is a strong pH booster, and how much will it raise the pH as pH can crash in a different direction too.
     
  6. Christophe

    Christophe Subscriber
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    The potassium should not be a problem at all.

    Keep in mind that pH follows KH, it's a secondary measurement. pH is sort of a loose indicator of what KH is -- CO2 also alters pH, and so do other things -- phosphate, sulfate, organic acids, etc. KH does not change significantly at all when you add or degas CO2. The carbonate still there, still measures at the same level.

    The reason certain fish get associated with a certain pH level is that they're adapted to specific osmotic conditions -- think dissolved solids. KH is part of that picture, and is usually matched more or less by GH (calcium & magnesium levels) in a specific environment. So, in natural conditions for your hard water fish, they have some relatively high level KH & GH. The pH, because the KH is high, also tends high. Adding CO2 doesn't change the osmotic character of the water, though it lowers the pH. You might gas the fish, but they don't die because the KH changed.
     
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  7. tiger15

    tiger15 Member

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    Good to confirm that high K shouldn't be a problem at all.

    True that pH, kH, TDS, GH and osmotic pressure are all related. But pH is not an equivalent measurement of kH. pH is an intensity measurement similar to temperature, whereas kH is a capacity measurement similar to heat capacity. So you cannot creat soft water simply by lowering pH with acid, you have to reduce TDS by mixing with RO water.

    But wrong intensity pH, similar to temperature, can kill fish as I witnessed my African cichlid died like fly when the pH dropped below 6.8 due to waste acidification even though the kH or osmotic pressure did not drop.
     
  8. Greggz

    Greggz Lifetime Members
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    I use K2CO3 to raise the KH of my RO water.

    The conversion is 4.5gm/1 Tsp. So 2.94gm is about 5/8 Tsp.

    That being said, that seems like an awful lot for your tank. How much water are changing at a time? If it's 50% change, you only need to dose for 30L. So 1.47 gm (1/3 Tsp.) would raise your KH by about 2.

    For reference, I add 3 Tsp to 80 gallons of water which raises the KH by 2.

    And like others have said, I wouldn't worry about the K. I'm guessing your plants will like it.
     
  9. Christophe

    Christophe Subscriber
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    I'd suggest it's not primarily the pH that killed your cichlids, pH was a related indicator of something else (acidifying waste) creating a toxic condition for them.
     
  10. Sangeeth Ramanunni

    Sangeeth Ramanunni Junior Poster

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    Thanks a lot.. thats helpful. But when adding for the first time, Shouldnt I add 5/8 tsp?

    Also is the same method to be followed for other ferts {macro and micro}? Need I onle add ferts for the additional water ? or for the whole tank voulme??
     
  11. Christophe

    Christophe Subscriber
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    Things that adjust water hardness, add only for the replacement water. Macros & micros, consider the whole system volume.
     
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  12. Sangeeth Ramanunni

    Sangeeth Ramanunni Junior Poster

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    Thanks
     
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