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Humidity levels?

Discussion in 'Everything Else Orchid' started by MiKa, Jan 1, 2013.

  1. MiKa

    MiKa Active Member Supporting Member

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    Thanks for all input. Really appreciate it :)

    I want to control it with a timer so I can have the unit working to decrease humidity at daytime and let the humidy rise during night.
    But as soon as the power is shut and then is turned on (by the timer) the unit has gone into standby mode. To start it I need to push the start button on the unit.
    I need to find a way to make it start as soon as the timer give it power.

    As I understand it, the dehumidifier then has to be running constantly. And that would be a bit energy wasting :)
     
  2. Ray

    Ray Orchid Iconoclast Supporting Member

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    Alexey, that's not entirely the case, as there is literally mechanical pressure across cell membranes that forces the movement of water. Yes, there is passive loss through stomata (which is what CAM plants attempt to overcome), and no, there is no massive, muscle-driven "breathing" going on, but there is symplastic movement of water and solutes through the plasmodesmata, and apoplastic transfer through cell walls and the intercellular spaces, which actually has less resistance to the flow of water. Once that happens, usually as a result of ionic imbalances resulting from nutrient uptake and the subsequent chemical processes within the plant, it "forces" more active transfer out through the roots and the plasmodesmata, as well as passive transfer through the stomata.
     
  3. oisifml

    oisifml Active Member

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    [​IMG]
     
  4. Alexey

    Alexey Well-Known Member Supporting Member

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    Ray, it would be great if we could make a progress in this discussion. However, we are back at the beginning: active root uptake is driven by ionic gradient, transpiration is driven by RH gradient. Extremely high RH in growing setup is anti-productive due to suppression of transpiration.
     
  5. oisifml

    oisifml Active Member

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    If you can bypass somehow the built in thermostat setting your machine has and use it only as a machine you can use the plug above to run your dehumidifier set it with a day humidity and have it shut at night so the humidity rises
     
  6. Ray

    Ray Orchid Iconoclast Supporting Member

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    Alexey, I guess we'll have to agree to disagree.
    Agreed.
    Not entirely, and this is where we disagree. It seems to me that if the ionic gradient draws water into the plant, that process would continue until the plant exploded. So where is it going? Some of it must be driven out through the plasmodesmata by the hydrostatic pressure it causes within the cells.
    I can agree in concept, but my own experience does not support that it is a real issue. My greenhouse has stayed above 90% RH for at least the last five years, and my plants are doing great.
     
  7. keithrs

    keithrs Member

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    The only way is to bypass or hard wire it inside the machine. I cant really give advice how to bypass it because I would have to see how it's wired inside the machine.

    What brand and model is it?

    If you know anyone who know electronics and wiring.... Give them a call.
     
  8. Alexey

    Alexey Well-Known Member Supporting Member

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    Ray, perhaps results can go from "great" to "superb" at the lower humidity levels. Plans slow their growth and loosing their rigidity/stiffness at the extremely high RH.
     
    Marni likes this.
  9. MiKa

    MiKa Active Member Supporting Member

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    I will open it up and see what I can do myself to bypass the electronic. I'ts a swedish brand. "Cotech".

    I am completely on your line here. Even though I grow many high humidity species like Lepanthes, Dichaea etc, I can see that they do better when grown where they experience differentiated humidity levels between day and night. And when it comes to other more dry growing species it seems even more logical that they suffer from extreme humidity.

    I have the dehumidifier going in the greenhouse since a couple of days and it lowers from 99% in the morning to 85% in the evening. Each 12 hour period the machine draws 18-20 liters of water from the air ( and my greenhouse is just 18 m²).
     
  10. Ray

    Ray Orchid Iconoclast Supporting Member

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    Possibly, but I have not noticed any loss of turgidity.
     
  11. Alexey

    Alexey Well-Known Member Supporting Member

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    Ray, plant turgidity reflects water metabolism, and its temporary issues can be observed at the extreme levels of RH. What I referenced, talking about rigidity/stiffness of the plant is a correlation between rate of transpiration and mechanical tissue development. Suppression of transpiration ( e.i. Due to high ambient RH) leads to permanent structural underdevelopment of new growth.
    In general, my point is: if we all are aware that extremes of light intensity, temperature, watering and use of fertilizers are non beneficial for orchids, why we shall advise extremely high RH as favourable? As any other parameter of growing environment it can be harmful and has to be maintained at optimal, not extreme levels
     
  12. Ray

    Ray Orchid Iconoclast Supporting Member

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    I have to agree with your general assessment, Alexey. Somehow though, I just think the RH issue is less critical. Maybe not unimportant, but possibly less so.

    And thank you for the exchange. In many forums, it degrades to the level of "Jane, you ignorant slut" almost instantly.
     
    ZWUM and Zack like this.
  13. Dave The Scientist

    Dave The Scientist Active Member

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    This thread might be dead, but it sounds like many of you know quite a good deal about the science behind orchids. I am always looking to learn so if any of you could suggest good reading on the subject, it would be great. Thanks.