Is GFO causing Alk to drop? Anyone else??

Discussion in 'Water Chemistry' started by FatBastad, Jan 18, 2014.

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  1. FatBastad

    FatBastad Zoanthid

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    So I've been using Red Sea Coral Pro salt. It claims to mix in the 11-12.7 range for ALK at 1.026.
    HA!
    Well, not my current batch anyway.
    Try 7...

    So maybe it's me, I'll explain.

    I've had two powerheads and a heater mixing at 1.026 in 5 gal of rodi water for a few days and tested tonight. (my typical routine)

    Am I simply leaving it mixing for too long?

    The calc and mag are also too high at that salinity as well.
    calc = 460 and mg = 1550
    Just about the exact same for those two in my DT tank as well.
    BUT my ALK was 5.6 the other night!!! :eek: Brought it up to 7.7 over 3 days.

    The plan is to bring my salinity down to .025 or .024 going fwd with this batch. Yes, I mix\stir the salt before adding it to the water too.

    So for my water change tonight I dosed some alk to bring it up and added about a gal of rodi to dillute it along with a portion of my system water.

    Admittedly I have more in the reactor now than usual due to some algae, roughly a cup vs roughly 1/2 cup per BRS calc as of about 2 weeks ago.
    I been using GFO for quite a while so I don't think I've shocked the system by doing so...

    So my question is, since my calcium and mag are high but alk is low, is the GFO in my reactor lowering my ALK?

    Has anyone else experienced this issue?


    Also, how long after dosing calc \ alk \ mag into the system does one have to wait before testing for accurate results? 15 mins? Hour or more?


    Thanks folks,

    FB
     
    Last edited: Jan 18, 2014
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  3. brentonwoodruff

    brentonwoodruff Fire Worm

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    I experienced the same problem with gfo and eventually set up a refugium and got rid of my reactor. One of the local reefers around here did the same for the same problem. This may have just started since you doubled the amount of gfo.

    According to Red Sea you should wait 10 minutes for parameters to stabilize before testing but I would wait 2-4 hours just so it is for sure stabilized and you are not changing things to quickly. Also track the values day over day testing at the same time each day since lighting and the resultant reactions cause water parameters to change throughout the day.
     
  4. FatBastad

    FatBastad Zoanthid

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    Thanks. Exactly the type of confirmation I was looking for.

    (I put on a fuge about 5 months ago with Cheato but due to the size I'm not sure if it will handle the entire nutrient reduction necessary, time will tell...)

    I'd still like to hear other folks input\personal experience with GFO - ALK issues...
     
  5. Mr. Bill

    Mr. Bill Native Floridian

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    I don't have any experience with GFO, but I did notice something worth pointing out--

    There's no such thing as 'mixing too long', within reason, of course. Worst case scenario, evaporation would raise salinity, but that, in turn, would raise all parameters exponentially. I would try a different test kit/checker, and if alk is really that low, contact Red Sea; it was only a few months ago that someone else got a bad batch...
     
  6. FatBastad

    FatBastad Zoanthid

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  7. oldfishkeeper

    oldfishkeeper Giant Squid

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    I dk, but another bump for you!
     
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  9. grinder37

    grinder37 Whip-Lash Squid

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    I've never experienced alk drop due to my gfo that i've ever been aware of and in my last two tanks I used Coral pro salt with gfo reactors.However,getting back into the hobby,I have changed back to reef crystals due to Coral pro's numbers never being consistent with the advertised jacked up levels.Seemed the mag was always decent,but the cal and alk bounced around from one batch to another,not drastically,but not consistent either.

    But,no,not in my personal experience have I ever had alk issues while running gfo that I could contribute it to the gfo or couldn't get it corrected.Now,if the amount of gfo you are using is causing this-idk :confused:
     
  10. evolved

    evolved Wrasse Freak

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    Yes, GFO will suck a bit of Alk, but usually only a little bit (maybe 1dKH) when it's brand new for the first few days of running it.

    It might be a contributor, but it seems there might be something else at work here.
     
  11. FatBastad

    FatBastad Zoanthid

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    thanks for the input folks.