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HUMIDITY IN THE GREENHOUSE

Discussion in 'Orchid Culture' started by chadders, Oct 5, 2021.

  1. chadders

    chadders Member

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    I grow orchids in a greenhouse in Napa County. The humidity can go as low as 10% at times during the year. To keep the humidity above 50% I installed two humidifiers and set the controls for between 60 and 70%. That keeps the humidity up but my well water contains lots of silica and it deposits on the orchid leaves. To solve this I installed a reverse osmosis system and have achieved 10 PPM dissolved salts in the water serving the humidifiers. I still get unsightly deposits on the leaves. Any suggestions? How do you keep the humidity up in your greenhouse. Thanks I appreciate your thoughts and expertise.
     
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  2. KellyW

    KellyW Orchid wonk Staff Member Supporting Member

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    Regarding the ongoing spotting, how do you fertilize? Also, do you use an insecticide? Both of those can cause bad spotting.
     
  3. chadders

    chadders Member

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    Kelly it's not spotting. It's a uniform layer of silica that looks like dust. It comes from the humidifiers that push water vapor into the air in the greenhouse. Thanks for your interest
     
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  4. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    In your introduction, I thought you said you used RO water for your humidifiers. If you are using low ppm water, there shouldn't be any new deposits coming from the humidifiers. You need to check your ppm frequently to be sure your RO system is functioning. RO membranes can go bad. It is also important to replace your prefilters frequently.
     
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  5. chadders

    chadders Member

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    Thanks Marni. I check the PPM in the humidifiers weekly. It reads 10 PPM on the meter which coincidentally I bought from you years ago. It has served me well. Thanks again.
     
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  6. chadders

    chadders Member

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    PS Marni, how do you keep the humidity up in your greenhouses? Your plants always look so beautiful.
     
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  7. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Thank you.

    Are you watering with RO water? It is important to calibrate your meter from time to time to be sure it is accurate. It doesn't make any sense that RO water in the mister would leave any residue.

    I use ultra-sonic misters for each greenhouse (they are placed outside) and use RO water to make the mist.
     
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  8. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    What is the ppm of your water before it goes through your RO membrane?
     
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  9. chadders

    chadders Member

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    I agree with your thinking that if the PPM is 10 for the water supplying the humidifiers there should be no residue on he leaves. The water straight from the well is 40 PPM. It is frustrating and I think there is something I am not taking into account. Thus I have turned to the Forum.
     
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  10. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    40 ppm is very low! Have you had your well water analyzed? Have you tested the ppm of the water that comes out of your membrane?

    Since I've never dealt with silica in the water, I did a quick google search on removing silica with reverse osmosis. It seems there are 2 types of silica, colloidal and reactive, and RO is better for the reactive silica. I think you would need to talk to someone with more knowledge than I have.
     
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  11. DPfarr

    DPfarr Well-Known Member

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    40 ppm is really low. Is there precipitate on non-biological surfaces near the mist exit?
     
  12. Ray

    Ray Orchid Iconoclast Supporting Member

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    AN RO system would likely remove all silica. Colloidal silica is a suspension, not a solution, so would likely be trapped by the prefilters before it ever got to the membrane.

    Dusty white layers tend to be carbonates, not silicates.
     
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  13. chadders

    chadders Member

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    Thanks all for your responses. The water right out of the membrane is 10 PPM. There is no precipitate on the humidifier output. I guess I will have to consult with the company that treats the well water for use in my house. Thanks again.