Calcium, alkalinity and magnesium

Discussion in 'Idol Marine' started by Idol Marine, 23 Dec 2014.

  1. Idol Marine

    Idol Marine

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    As a reef keeper you need a good understanding of Calcium, Magnesium and Alkalinity in order to maintain a stable and balanced supply of building blocks for your corals. Not only does it affect the growth rate of your hard corals, but also colour and overall health of your corals.

    These elements are extracted from the water by the corals when they grow and lay down to build their Calcium Carbonate skeletons. Take note…Calcium Carbonate (CaCO3) skeleton. Corals need these elements in a balanced supply in the water. They cannot grow if one of these elements are too low, which is why Balance is so important.

    So one should always strive for stability! You must not let the concentrations of these elements in the water seesaw up and down, because this inhibits coral growth.
    This is where regular testing comes in (once a week). The recommended range for alkalinity is 2.8- 4 meq/L or 7 - 11 dKH.

    Alkalinity also gets depleted due to the fact that it neutralizes all the acids produced in the system, (fish urine to name one).
    Due to this, alkalinity has to be monitored very closely because of the 3 elements we talking about it “gets used up” the most.

    For this reason it is also called a pH buffer due to the neutralization of acids and for that the pH stays nice and stable, much more than in fresh water.

    For calcium, the range should be 400 – 430 ppm calcium.

    Magnesium is important because it stops the calcium and carbonate (alkalinity) from precipitating out of solution. You could use the analogy of it being a lattice, making sure your Calcium stays in solution.
    For this reason you should keep your magnesium levels between 1320ppm to 1370ppm.

    Calcium reactors

    Calcium reactors bring stability because of gradual daily dosing of calcium and carbonate.
    Calcium reactors use a Calcium Carbonate media (same as your coral’s skeleton). We add CO2 to this to form Carbonic Acid that dissolves the Calcium Carbonate media back in to the water as free Calcium ions and Carbonate ions so the corals can use it to build their skeletons. This basically reverses the process of corals growing.

    How it works:

    The kit consists of a reactor, Calcium Carbonate media, CO2 bottle, solenoid valve, pH probe and pH controller.

    Aquarium water gets pumped slowly (depending on aquarium volume and coral demand) through the reactor that is filled with calcium carbonate media. CO2 gets added to this in a controlled manner by the controller to bring and keep the aquarium water with a pH of round 8.2 down to round 6.5. Now the media in the reactor dissolves slowly due to the acidity of the water. The lower the pH of the water the faster the media dissolves. This way you can keep up with the ever increasing demand of the system because the corals get bigger and their ever bigger demand for more calcium carbonate.

    It is important to remember that a Calcium reactor does not fix imbalances, but rather maintains your Calcium and Kh (carbonate) levels, and it always advisable to make sure you have the correct balance of Calcium and alkalinity in your tank before you start the reactor.

    Below are some pictures of Calcium reactors.

    carx 1.jpg

    carx 2.jpg
     
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  3. Carcharias

    Carcharias

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    Hay there guys. I have been using NeoMag from Brightwell that I mix in with my Calcium media to also help maintain Mg. I have found that this works for me.
     
  4. Idol Marine

    Idol Marine Thread Starter

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    Perfect! Works very well!
     
  5. TaahirS

    TaahirS MASA Contributor

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    @Idol Marine nice article, thanks. They are always very informative.
     
    Last edited by a moderator: 26 Nov 2015
  6. dallasg

    dallasg Moderator MASA Contributor

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    i like using the carib sea course material, has the right ratio of Mg, Ca, Sr
     
  7. Adee

    Adee

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    Regarding mixing in NeoMag (from Brightwell) along with CaribSea coarse media...I always find the calcium media dissolves away...yet the magnesium media stays behind, as if nothing happens to it.

    Does the lowered PH (I keep my CARX PH at 6.3) affects the mg (dolomite) less, than that of the calcium (aragonite)?

    Assuming one would mix in calcium and magnesium media in a CARX....what sorts of ratio should the volume be split up, and what would be the prescribed PH setting? I have a medium to heavy daily requirement, in terms of my Ca, Mg & Alk needs.
     
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  8. carlosdeandrade

    carlosdeandrade

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  9. Adee

    Adee

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    Ahh cool....I thought i was the only special one :whistling:
     
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  10. carlosdeandrade

    carlosdeandrade

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    Arm media dissolves at a pH of around 6.7. There is media that will only dissolve at 6.2. In terms of the Mg, Brightwell suggest that you would use Neo mag at a ratio of 9:1. In other words 9 parts of arogonite to one part Neo mag. Either in the main chamber, or if you have one of those fancy reactors, in the Magnesium chamber.
     
  11. Adee

    Adee

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    Thanks, that what i started with some years back and then increased it to something like a 70:30 split ratio, as I was finding that I was still dropping Mg and having to top off Mg manually.
     
  12. Ridwaan

    Ridwaan

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    Same here...found the mg media staying the same but ca media was dissolving...
     
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