Kh?

Discussion in 'Water Chemistry' started by fishoholic, Dec 2, 2008.

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  1. fishoholic

    fishoholic Purple Spiny Lobster

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    I tested my pharms today, everthing is good except the kh which is at 7. I've read on other posts that some keep theres between 12-15 is the right? By being at 7 what does it effect compared to being at a 12 or so? What should the kh be in a reef tank and how do you raise it? I supplement reef carbonate twice a week is there a better method? TIA
     
    fishoholic, Dec 2, 2008
    fishoholic, Dec 2, 2008
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  2. missionsix

    missionsix Super Moderator Staff Member

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    7 isn't a "bad" #. Make sure you are testing magnesium before you go and fudge with your Kh.
    A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com
    Alkalinity is a complex measurement. It is not a "thing" in the water. It is actually the summation of many things, all of which together provide a particular chemical property. The reason that aquarists measure alkalinity is that in normal seawater, most of it consists of bicarbonate and carbonate. Bicarbonate (HCO3[SIZE=-1]-[/SIZE]) is what corals take up and process into carbonate (CO3[SIZE=-1]--[/SIZE]) in order to build their calcium carbonate skeletons. Consequently, alkalinity is an indication of whether or not adequate bicarbonate is present in the water.
    Normal to high alkalinity implies adequate bicarbonate, while low alkalinity implies that it may be in short supply. In the absence of any method of supplementing alkalinity in a reef aquarium, the water can rapidly become depleted of bicarbonate. Alkalinity's depletion from normal to unacceptable levels can take only a day or two in some reef aquaria, although it can take longer in aquaria with a lower demand for carbonate. When the water's bicarbonate is depleted, corals that deposit calcium carbonate can become stressed and even die. I recommend that reef aquarists maintain an alkalinity of 2.5-4 meq/L (7-11 dKH, 125-200 ppm calcium carbonate equivalents).
     
    missionsix, Dec 2, 2008
    missionsix, Dec 2, 2008
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  3. PharmrJohn

    PharmrJohn The Dude

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    Yeah....read that article. Mission has pretty much said it. It's an indirect measurement of bicarb. I keep mine between 12 and 15 and my system will deplete by a unit of "0.75 to 1" per day. So I let it cycle between those two numbers. Some corals such as Xenia like dKh around 12. Others will not tolerate levels above that so much. You will know once you start experimenting with the levels a bit. There is an individual on the forum who has an SPS tank that keeps his around 25. Ten to twelve are good numbers to aim for IMO.
     
    PharmrJohn, Dec 2, 2008
    PharmrJohn, Dec 2, 2008
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  4. reef_guru

    reef_guru Humpback Whale

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    its dKH not kh

    having the correct balance between Ca,Mg,dkH,K,Sr is important. nsw is a nice target but can be higher. so, with dKH around 12 or even 25 its important to have the ratio of elements match
     
    reef_guru, Dec 2, 2008
    reef_guru, Dec 2, 2008
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  5. fishoholic

    fishoholic Purple Spiny Lobster

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    Ca-480
    Mg-1440
    dkh-7
    Are these pharms at the correct ratio for each other?
     
    fishoholic, Dec 2, 2008
    fishoholic, Dec 2, 2008
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  6. PharmrJohn

    PharmrJohn The Dude

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    The ratio between Ca and Mg is about 1:3.25. So with a 480 Ca (which is a good value), your Mg would want to be around 1560. I would raise your dKh to between 10 and 12 also.
     
    PharmrJohn, Dec 2, 2008
    PharmrJohn, Dec 2, 2008
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  7. Dr.Fragenstein

    Dr.Fragenstein Panda Puffer

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    kH is typically the most used acromyn for carbonate hardness and dkH is the German unit for it degrees of carbonate hardness.
    Most shoot for 8-12 when you start getting higher it is tougher to maintain a high pH and and Ca w/o issue. People that run high alkalinity then to have depressed pH say 7.8 tops and will occasionally see swings in Ca as that can fall out solution.
    Keep in mind you can only fit so much "stuff" in water before you have too much.

    Good luck
     
    Dr.Fragenstein, Dec 3, 2008
    Dr.Fragenstein, Dec 3, 2008
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  8. fishoholic

    fishoholic Purple Spiny Lobster

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    Thanks very helpful
     
    fishoholic, Dec 3, 2008
    fishoholic, Dec 3, 2008
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  9. fishoholic

    fishoholic Purple Spiny Lobster

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    Thanks very helpful
     
    fishoholic, Dec 3, 2008
    fishoholic, Dec 3, 2008
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