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Thread: Kh

  1. #1
    Member Dockery's Avatar
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    Kh

    what is it? should it be high or low? how does it effect other aspects of the marine aquarium? soory for the dumb question!

  2. #2
    Senior Member clown_fish's Avatar
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    I think a good range is between 8dKH - 10.5dKH this relales directly to calcium which is usually be kept between 380 - 450.
    Natual sea water has alk around 8dKH and calcium ~ 400.
    90G bb mixed reef set up in April 2005. I had 40g mixed reef for one year before that

  3. #3
    Member Dockery's Avatar
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    thx, I'll give my water a test

  4. #4
    Moderator Krugar's Avatar
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    We can't actually match the ocean in a closed environment. Not keeping the Alk & Ca chemically balanced leads to rock hard sandbeds and white deposits building up over time.

    The balance between Alk & Ca isn't linear, I have to use a calculater like this one:

    http://home.comcast.net/~jdieck1/chem_calc3.html

    Anway at 8dKH (about 2.86 meq/l) the balanced Ca is 420ppm.
    400 ppm Ca has a balanced Alk of 1.96 meq/L which equals 5.5 dKH. (meq/L x 2.8 = dKH)

    5.5 is too low for a reef tank, so you should try to keep the tank balanced at ~ 420 Ca and 8 dKH although you can go higher. 11dKH is balanced ~ 440 ppm Ca.

    The tricky bit is the balance. Even if you're using a balanced additive, the living creatures in your tank will not use them in balance. Sometimes they need more of A, sometimes they need more of B. Over time they tend to balance but you still need to test or you can end up with a rock hard sand bed deposits in your pumps.

    Ideally you should have have a consistant balanced additive going into the tank. (Dripping kalk, adding anything 2 part on a regular basis, etc) and test weekly or so & top off what ever drifted out of balance.

    That's the "text book" version. The real life version is getting there is challanging and can cause problems. So you need to figure out if it's broken before you fix it. I'm a big believer in "if it ain't broke.. don't fix it."

    Cheers!
    There is nothing so permanent as a temporary measure.

  5. #5
    Moderator Krugar's Avatar
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    Doh my computer developed a sense of humour during my spell check. Sorry for the creative English there

    Cheers!
    There is nothing so permanent as a temporary measure.

  6. #6
    Senior Member Ricepicker's Avatar
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    IMO not something you can very well worry about too much, though if you Kh is too high, you get this cementing of the substrate, forms these concrete pieces, which really sucks for circulation.

    living things in general have what is known as limiting factors, so thats why its preferable to keep both balance in a specific ratio so they don't use up all of one.

    different parts of ocean has different ratios of Ca2+ to kH, so i dunno if theres a golden rule for marine tanks, its best to just watch the tank to determine wrether you need it or not

  7. #7
    Senior Member mickyfin's Avatar
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    Disagree.

    Measuring your KH in accordance with CALC and PH is an improtant way to keep your tank in the correct BALANCE and ensure coral health and growth.

    KH is short for dKH an Abbreviation for Degrees of Carbonate Hardness.
    www.kingvinnie.com/aquaria/glossary/
    Don't Panic Feel free to visit my blog -> Internet Tough Guy.

  8. #8
    Moderator Krugar's Avatar
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    I more or less agree with ricepicker.

    Ca & Alk are extremely important, but there are several great examples of reef tanks where the carbonates are consistantly under 8 dKH and the Ca is around 375ppm or so. Under 400 anyway.

    Some tanks reach their equilibrium by dosing what the corals are taking out. i.e. matching consumption. Textbook theory suggests that if you've found this point then adding a bit more will bring up your numbers & bring them into balance.

    Real life isn't always that simple though.

    Not having your ca & alk balance will cause issues with deposits forming & your sand bed hardening. But those can be managed. Sometimes those issues are easier to manage than balancing your alk & ca.

    Cheers!
    There is nothing so permanent as a temporary measure.

  9. #9
    Senior Member Ricepicker's Avatar
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    Quote Originally Posted by mickyfin
    Disagree.

    Measuring your KH in accordance with CALC and PH is an improtant way to keep your tank in the correct BALANCE and ensure coral health and growth.

    KH is short for dKH an Abbreviation for Degrees of Carbonate Hardness.
    www.kingvinnie.com/aquaria/glossary/
    pointless if the corals can't utilize it. besides, different coral have different need, you can't satisfy them all, that "balance" you speak of is more or less a generalized average.

  10. #10
    Moderator Krugar's Avatar
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    IMHO, keeping the ratios perfectly balanced is more about protecting our systems than keeping the corals happy.

    I just tested my water. I'm at 9.8dKH and 410ppm calcium. I am out of balance, I need to either lower my alk or raise my calcium to 430ppm. Raising my Ca is the easier of the two.

    Anyway, I really don't think anything in my tank cares about the 20ppm I'm missing since I'm over 380ppm. There's plenty for the corals and it's pretty close to the right ratio.

    So the balance becomes more important because I don't want my sand bed to turn into cement or my pumps to seize up with deposits. I'll likely add some calcium in a couple minutes.

    But who's benefit was that for?

    Cheers!
    There is nothing so permanent as a temporary measure.

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