Pearling with High Turnover?

Discussion in 'Filters, Filtration and Pumps' started by Superman, 21 Aug 2008.

  1. Superman

    Superman Member

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    I've noticed that on the underside of my plants are producing oxygen bubbles, but the upper surface is not.

    I'm wondering that in higher turnover tanks you might not see larger oxygen bubbles, as the oxygen is produced on the surface it'll be dissolved into the water quickly, due to the amount of water that passes over the leaf?

    I'm seeing my vallis pearl as they're under the filter output but other plants, I don't really see pearl much.

    Is my thinking correct?
     
  2. Joecoral

    Joecoral Member

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    That sounds like a reasonable assumption to me. I don't know for definate either way tho
     
  3. Dave Spencer

    Dave Spencer Member

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    O2 isn`t particularly soluble in water, so my guess is that the plant is producing it quicker than it dissolves. My Rotala sp can be covered in the stuff, yet there will be minimal amounts on my Pogostemon helferi, so the different rates of photosynthesis may come in to play, too.

    Dave.
     
  4. Ed Seeley

    Ed Seeley Member

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    Higher turnover rates should reduce the boundary layers surrounding each leaf meaning that you don't get the locally saturated conditions that see the Oxygen bubbling because, as Dave said, it isn't that soluble in water. Increase the flow, you increase the mixing and therefore increase the dissolving of the oxygen into the water.

    You can still get pearling though, just depends on the tank conditions.
     
  5. plantbrain

    plantbrain Expert

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    I get a lot of pearling even at 15X turn over per hour.
    But I have high light and fast growth, that, really determines a rate of pearling, basically the faster the rates of plant growth, the faster they will pearl and give off O2. Plants give off O2 out of their stomata which tend to be on the bottom of the leaves, not the top, water lilies are the exception and a few other aerial floating leave plants etc.

    Regards,
    Tom Barr
     
  6. GreenNeedle

    GreenNeedle Member

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    Is it not also a case of rather than the plant pearling the bubbles can be trapped underneath the leaves?

    My ideaof pearling is similar to a diffusor in that small bubbles rise from the leaf. What I can often see in my own tank are large bubbles underneath Anubias etc which are just like the large bubble that sometimes gathers under the diffusor itself. I assum the diffusor isn't pearling ;)

    On another note, I have my Lily only half submerged and it brings O into the water (waterfall noise meand the whole house is constantly going to the toilet. lol.) Once these get caught by the flow these also manage to be pushed all around the lower regions of the tank and maybe adding to the 'trapped' bubbles effect.

    I'm not sure if I get pearling or not. I know that bubbles and leaf surfaces are sticky. I get bubbles of CO2 'sticking' to the leaves (I think) rather than the leaves releasing them.

    AC
     
  7. Superman

    Superman Member

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    Monday Night = Water Change Night

    So filter off and there's loads of oxygen bubbles rising once the water is still. I'm very happy :D
     
  8. GreenNeedle

    GreenNeedle Member

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    is this before or after the water change?

    You should always get a certain amount of 'pearling' after water changes due to the O in the water.

    AC
     
  9. Superman

    Superman Member

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    Thanks Andy, think that discussion was covered in my journal.

    Some was pre water change but most of it was after.
     

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