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Neutral Regulator and potassic bicarbonate

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  • Neutral Regulator and potassic bicarbonate

    Hello, I have a 120 liters fresh water not-planted tank with six corydoras, two ancistrus and two carassius auratus, with 2 cm sustrate JBL Manado, 2 cm sustrate JBL Sansibar River, two non limestone rocks, and a rootsunk. About three weeks ago the aquarium stopped nitrifying, and after investigating a while, I detected that the city's water supply varied substantially by parameters, dropping the pH from 7 to 6, and really low KH and GH values. I decided to start using Neutral Regulator to set pH to 7, and Replenish to increase GH. The problem is that the pH has not stabilized, it is still somewhat low, at 6.8 and I have used potassium bicarbonate to increase the KH to 4 dKH. My question is: is potassium bicarbonate compatible with neutral regulator, and if so, how should I use them?

  • #2
    Thanks for the post, david_ps!

    In freshwater, there are typically two main types of buffering systems, phosphate and carbonate. Unfortunately, the two systems don't get along very well and will fight against one another for pH control. Since you added the potassium bicarbonate, the NR is likely having a hard time adjusting due to the bicarbonates in the water. Alkalinity (ability to maintain pH) in freshwater can come from several different buffering ions, KH (carbonate/bicarbonate) or phosphates. As long as you have alkalinity in the system (either of those two), your pH should remain stable and by adding the NR, you are adding alkalinity by way of phosphates and not carbonates (KH). Since you don't have live plants, not having a KH is perfectly fine. You will be able to maintain the pH by only using the NR because it is also adding alkalinity. I don't think it is necessary to also add the potassium bicarbonate for KH, as they are going to fight against one another and make it difficult to stabilize the pH.

    Hopefully this all makes sense, but if you have questions let us know!


    • #3
      Thank you very much. Only one more question: what is the PO4 concentration (mg/l) with a correct buffering system with Neutral Regulator?


      • #4
        No worries! Each dose of the Neutral Regulator will add a significant amount of phosphates to the water, however, because the buffer is so stable, you don't have to add it frequently (typically once a week at water changes is sufficient to maintain the pH). Therefore, the concentration of PO4 should not cause any issues i.e. algae.