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Maintaining kH and GH with Reef Reactor

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  • Maintaining kH and GH with Reef Reactor

    For about two years now I have been putting small filter bags filled with crushed coral/shells substrate in my Ocean Clear filters on top of the Matrix. The 6.5 pH slowly dissolves this and I manage to keep both kH and GH at just around 10 degrees, keeping up with the periodic partial water change schedule I am on. All the alkalinity is owing to actual carbonate and I have found that I never need to use bicarb buffer to adjust the kH. I dose Mg and K in regular small amounts. I never dose Ca except as it occurs in the micronutrient supplementation I use. The K is always around 50 ppm, never lower than 40, and the Ca:Mg is about 2:1.

    I am now experimenting with Reef Reactor (Md), using it in place of the crushed coral aragonite. I am interested to see how it keeps up the K and Mg without my dosing so much sulfate. I have the general idea that Reef Reactor will perform the job that the crushed coral has been doing with this added benefit. The strontium will probably rise as well - to concentration not normal to freshwater. While I doubt there is a problem with that, I am curious to know your thoughts on this.

  • #2
    Thank you for your post. This is not its intended purpose so it is difficult to predict results. Keep in mind that it will release high levels of calcium, magnesium, strontium, potassium, and carbonates into the system and that it is designed to help replace these nutrients lost from coral utilization in a reef system, so in a freshwater tank, levels can easily become extremely elevated (out of desired range).

    We will be interested to hear feedback from your testing!


    • #3
      I think just now my two questions are

      1.) Is Reef Reactor more soluble than the crushed shells substrate? I am expecting to see similar system behavior, but with a possibly different water change interval.

      2.) Can I expect that Reef Reactor is quantitatively uniform and delivers consistent concentrations (i.e. the ratios are constant whatever the absolute values)?

      Regarding Sr, I have done some research and have no concerns about it. It does occur in natural freshwater and freely substitutes for the other alkaline-earths, incidentally accumulating in plant tissues with no apparent toxicity.


      • #4
        Hey Paul,

        1) The crushed coral is likely to have more available surface area, so I'd suspect that it would dissolve faster than the Reef Feactor, but it will depend on what kind of crushed coral you are comparing to.

        2) You can!

        Thank you,


        • #5
          I am having trouble posting replies. This is a test.


          • #6
            One month into this experiment, observations so far:
            1.) This system goes about ten days from a conductivity of 1.40 mS/cm to 1.46 mS/cm. A 10% water change (RO/DI) resets the cycle. The kH correspondingly goes from 9 to 10 deg (160 to 180 ppm CO3), and the calcium goes between 140 to 160 ppm. No sodium bicarbonate buffering or additional calcium supplementation are needed. Reef Reactor is doing a good job of maintaining stability.
            2.) This cycle is not different than with the crushed coral, so it appears that the difference in solubility is not pronounced. Reef Reactor does NOT cause runaway hardness at pH 6.5 - 6.6.
            3.) It is necessary to dose MgSO4 and K2SO4 much as before. While Reef Reactor is contributing Mg and K, it does not suffice as sole supplier. This system has well over 200 ppm sulfate, as I suspect many planted tanks do with regular dosing. The sulfur requirement of the plants is far exceeded by the available sulfur. Ideally, I would like to see increased yield of Mg and K cations from dissolution of carbonate. But until such a variation on this product comes along it will be necessary to dose the sulfate salts as usual.


            • #7
              Thank you for the update!