weight of rock wet vs dry

Discussion in 'Live Rock' started by Peredhil, Dec 7, 2009.

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  1. Peredhil

    Peredhil Giant Squid

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    I am trying to find some ratio's of how much heavier a saturated rock is than a dry rock.

    I'm having a hard time finding that - maybe I am using the wrong words for google :confused:

    Has anyone weighed the same rock bone dry as well as after it had been submerged for some time?

    Or know of a good article on this. I'm thinking along the lines of "good base rock should hold x% of its weight in water" or something. I guess it would be a measurement of density indirectly.
     
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  3. Av8Bluewater

    Av8Bluewater Giant Squid

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    I don't know but have always wondered. I'm sure it varies depending on type of rock.
     
  4. coylee_17

    coylee_17 Fire Goby

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    I have seen that before, and I know its on a thread here somewhere because I posted it lol. Let me see if I can find it.
     
  5. Gresham

    Gresham Great Blue Whale

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    my thoughts as well.
     
  6. coylee_17

    coylee_17 Fire Goby

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    1 person likes this.
  7. GuitarMan89

    GuitarMan89 Giant Squid

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    I agree with those numbers, but it also depends on the type of rock, Florida rock is denser to begin with so it won't absorb much water, while Fiji rock is less dense and will thus absorb more.
     
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  9. Peredhil

    Peredhil Giant Squid

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    thanks for the help so far.

    I agree it varies by rock... it would have to. 25-40% seems awfully high to me...

    I wonder if any one has backed that up.


    I don't have any rock to sacrifice for this... but it should be fairly simple test. Take rock out of tank, weight it. Set rock to side for a couple of weeks, weigh it again. Apparently a 10 pound rock will only weigh 7 pounds dried (if it is on the 40% side of the scale).

    7 lbs x 1.40 = 9.8 (which is close enough to 10 for me).

    So a 7 lb rock would weigh 10 pounds (more or less) soaking wet... I have a hard time buying that a 7 pound rock can hold 3 pounds of water (about 1/3 gallon)... but a weight test would convince me.

    I'll make a deal. If someone does this test for me (with a reef rock at least over a pound), I'll sacrifice a piece of my Texas Holey Rock and see how that compares (I've been really curious about the comparisons lately).
     
  10. Gresham

    Gresham Great Blue Whale

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    I have access to oodles of dry rock of various origins. I'll see if I can do this for you... if I can scare up the time.
     
  11. Peredhil

    Peredhil Giant Squid

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    excellent ;D;D;D
     
  12. coylee_17

    coylee_17 Fire Goby

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    I'll gladly pull some live rock out of the tank, just gotta find a scale, I think my mom has one of those deli scales from her old store, I'll give her a call.