Alkalinity dropping all the time, yet calcium etc. holding

Discussion in 'Reef Aquarium Discussion' started by pmaddox, Mar 14, 2017.

  1. pmaddox

    pmaddox Member

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    For some time now i've experienced a constant drop of my Alkalinity although my Calcium and Magnesium do not drop remotely as fast.

    It's perplexing.

    Does anyone have experience or insight as to what could be causing this?
     

  2. morpheas

    morpheas Well-Known Member

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    What kind of drop are we talking about? It's normal for alkalinity to move much faster than calcium (and definitely magnesium). Do you have any numbers to share? Also what volume system? SPS, LPS, softies?

    @Randy Holmes-Farley has excellent articles in the interwebs like this one.
     
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  3. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    Unless you monitor for an extended period, a hobby calcium kit may not accurately detect the small calcium drop (13 ppm) that is associated with an easily detected 2 dKH drop in alkalinity.

    Otherwise, there are a few ways alkalinity can decline and not see a calcium drop, such as increasing nitrate (not just high, but actually rising) or the use of a sulfur denitrator. :)
     
  4. pmaddox

    pmaddox Member

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  5. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    What are you dosing?
    What salt mix are you using for water changes?
     
  6. pmaddox

    pmaddox Member

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    I have been dosing Seachem reef builder Alkalinity and I use Reef Crystals (Instant Ocean) salt. It looks like I drop about .20 dKH per day. 200 gallons of water (not counting any displacement)
     
  7. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    0.2 dKH per day?

    You'd wait a long time to detect a calcium drop. It would only be about 1.3 ppm per day, so it might take a few weeks to reproducibly see a calcium decline using a hobby kit.
     
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