Using fans without drying out tank?
 

Hello friends,

I recently repurposed a large ikea cabinet to use as an enclosed orchid space, so I can grow with LED lights. Inside, I mounted a small usb fan to provide air circulation. My issue is this the fan dries out the enclosure too much.

I do not have a misting system, aside from my own misting bottle (used daily, sometimes twice) mainly because these are not *high* humidity orchids - but regardless, they can't be too happy with the low humidity and high LED light. It is *too* much of a wet/dry cycle.

I have started to keep the fan running during the day, but turn off at night to allow some of the humidity raise @ night, naturally.

Unconventional question: is a fan necessary if the enclosure is not air tight?

Nat

It depends. If you're needing to water every day the air circulation is probably adequate without a fan.

Thanks ES. This is part of my thought. The lights run quite warm, so they mount and lose bark orchids do dry out within a day. With the fan, it is reaching twice a day. Maybe turning the fan off for a few days and seeing how it fares?

Another note.
Does the fan also help alleviate any sun stress from the warmth of the lights? By cooling down the leaves? I made the mistake of not acclimating my Blc. Yellow Bird more slowly and it is suffering some pink pigmentation. I can post a picture later.

Pink pigmentation is common in many Catts. Yellow Bird has Brassavola ancestry, and thus can take more sun than most other orchids. The light level is probably fine.

A fan will indeed keep the leaves cooled to ambient temperature. You can grow under brighter light, or sun, with a fan.

You will have to show a picture.
Depending on the time of day it seems you will get different answers to this question - with a picture the anwer will be more precise as I know I asked this question before and got all answers under the sun.
I grow in an Ikea case myself, wasn't easy getting things right but low humidity is rarely an issue. I have to leave the door open a crack all the time to prevent humidity rising and I heat it. I am suspecting your light is far too hot. I am also suspecting your fan is too strong. As to your question whether it helps cool leaves from the sun = yes, will it prevent LED light damage? = no.
Led light is cool so does no heat the leaves but if it is too strong it can cause leaf bleaching. A fan will make no difference to this. A fan will only cool a leaf to stop it getting a sun burn. light can burn by being too intense or by being too hot. An led will only burn by being too intense.
I try to get away without using a fan as much as possible - I have found I could not get away with it in the Ikea case, mainly due to the size - the fan helps maintain an even temperature and humidity throughout the case which I would not be able to do without. So I think you need one.

I have a very simple fix for your humidity problem but I want to hear how strong the light and the fan is first. There shouldn't really be a low humidity problem with a low heat light and very weak fan.

Plants don’t sweat like people, so fans do only a minimal amount of cooling.

It sounds like you have the fan directing dry, outside air into the enclosure, when all you really are after is internal circulation, and only a mild breeze at most.

Yes, use the fan to circulate air inside the case only. I assume the usb cable is plugged into some sort of power supply that goes to an AC outlet, get a timer for that, you should be able to turn that fan off and on multiple times a day.

Have you considered putting in a humidity tray of some kind? Placing a tray with a layer of LECA partially sitting in water in front of your fan will help keep humidity up. Without circulation in an enclosed space, you run the risk of stagnant air and all the problems that come with it.

There are no fast and solid rules for this.

I have a small terrarium (12” diameter x 15” tall glass cylinder) on my desk, containing a couple of mounted plants. I water with a hand sprayer a couple of times a day. It has an overhead LED plant light, and that’s it. There is a 2” layer of saturated LECA at the bottom.

Even with a plexiglass cover on the top that leaves a 1/2” gap in the middle, tapering to a close at its ends 3” in either direction, the plants are dry within an hour. If I leave to top off, it’s minutes.

Orchidtinkerer, I am attaching a photo here.

Thank you all.
I had the fan inside of the cabinet. So it was circulating the air inside, and I am sure, drawing & pushing some air from outside, since the doors are not air tight.

Even without the tray the RH is roughly 60% daytime, and 75% nighttime. It is good, but I think a humidity tray contraption is the answer here. I found some egg crate dividers and silicone drip boot trays that are large enough to cover the shelf. Hopefully that helps?