Mister, fogger, or other solution to raise humidity in 18 x 18 x 24" Terrarium? - Orchid Board

subtle_variegation · #1 04-22-2024, 01:53 AM

I recently purchased a used 18 x 18 x 24" Exo Terra terrarium for my small collection of (mostly) miniature orchids that I grow indoors. It holds some moisture after I water my plants but the increase in humidity doesn't last long (I'm currently using the mesh lid it came with and a small USB fan for ventilation). I'm looking for some cost-effective recommendations for something that allows me to keep the RH consistently higher.

From what I've read fogging systems are better than misters because the droplets are much smaller and therefore less likely to contribute to bacteria, mold, fungi, etc. However, I also know that the MistKing systems are pretty popular and have very fine mist.

I found someone selling one of their starter systems (I think it's the V4.0, not the newest one) for only $100 on Facebook Marketplace. That's probably the maximum I want to spend right now, if I could be closer to $50 that would be better. I'm a little suspicious of the cheap models on Amazon because of all the mixed customer reviews. I know I could buy one of those small desk humidifiers but I'd prefer something with more controls/automation (e.g. a timer).

Any suggestions would be greatly appreciated!

Ray · #2 04-22-2024, 07:55 AM

With that setup, you’re fighting yourself, as any extra humidity will be removed pretty quickly with the action of the fan.

The interior volume is maybe 4 cubic feet, assuming the plants and “furniture” take up some of the volume. If your fan is moving more than about 4-5 cfm, it’s probably too much. In fact, with an open top, you may not need it at all. The idea behind air movement is to prevent pockets of stagnant air, or to cause a breeze. Maybe set the fan to draw less air out of the top, which will slow the flow of air in, displacing less of the humidity?

Personally, I’d use a small ultrasonic fogger in that enclosure.

subtle_variegation · #3 04-22-2024, 03:08 PM

I see what you mean about the fan, I bought it kind of prematurely because I'm planning on eventually switching the mesh top to glass or plexiglass to keep in more humidity. The fan is pretty low power though and the room that the enclosure is in doesn't always have the main fan on. I'm also paranoid about rot because these orchids are used to a dryer environment (which has not been good for them hence the new setup).

You mean something like this, right? That could work, the only thing I don't like is having to use a smaller reservoir that would probably need refilling often.

Another option that I saw on YouTube is attaching a funnel to an ultrasonic humidifier and running connected tubing into the enclosure. This would be good since I can use a larger reservoir.

The seller on FB is willing to come down to $60 for the kit and a timer. So, that would come out to be a similar cost to the humidifier setup. Would that be a better option?

Ray · #4 04-23-2024, 08:27 AM

If you are willing to attach an external device to raise the humidity, consider this:

Install a mini float valve in the plastic container you saw in the Youtube video. That will maintain the water level and you don't have to refill it manually. You can DIY with the fogger and an ordinary bucket. The float valve is available from usplastic.com

If you make the tubing/ducting to the vivarium a bit larger and enclose the top with plexiglass, the fan will draw humidified air through it into the tank.

subtle_variegation · #5 04-23-2024, 03:41 PM

Oh, that's another interesting idea. Do you mean attaching the float valve to the humidifier or using the ultrasonic mister? Sorry, I'm having a bit of trouble visualizing it.

Just curious, is there any reason you wouldn't recommend the MistKing? It seems to be a pretty comprehensive system that could yield itself to further automation in the future and the price point the seller is at now would only have me spending a little more than the DIY options.

Ray · #6 04-23-2024, 05:47 PM

Imagine a bucket with a float valve in the side. The valve is connected to a water supply so maintains the water level as the ultrasonic fogger turns it into fog, which is then drawn into the Exoterra by your exhaust fan in the top,

I am a fan of Mist King and used one in a "plant hospital/incubator". The lowest level Mist King starter kit easily watered (not just humidified) a 72" x 36" x 36" volume. I think it would be overkill in your application and will wet things down, rather than just boosting the humidity.

Dusty Ol' Man · #7 04-24-2024, 11:07 AM

As far as controlling humidity goes, you could add a humidistat and connect a small humidifier to it. Pictured is mine. It works very well.

subtle_variegation · #8 04-25-2024, 02:04 PM

Quote:

Originally Posted by Ray

Imagine a bucket with a float valve in the side. The valve is connected to a water supply so maintains the water level as the ultrasonic fogger turns it into fog, which is then drawn into the Exoterra by your exhaust fan in the top,

I am a fan of Mist King and used one in a "plant hospital/incubator". The lowest level Mist King starter kit easily watered (not just humidified) a 72" x 36" x 36" volume. I think it would be overkill in your application and will wet things down, rather than just boosting the humidity.

Oh, I see. I guess what I don't understand is why I wouldn't just use tubing to feed the fog directly into the tank (via a humidifier)?

I went ahead and bought the MistKing because it was such a good price but I may just sell it. I definitely don't want things to be overly wet. I would like to experiment with automated watering in the future but with the added humidity I probably won't have to water as much as I do now.

---------- Post added at 01:04 PM ---------- Previous post was at 01:03 PM ----------

Quote:

Originally Posted by Dusty Ol' Man

As far as controlling humidity goes, you could add a humidistat and connect a small humidifier to it. Pictured is mine. It works very well.

I definitely would like to get something like that. Is it automated to where the humidifier only runs enough to maintain the humidity you set it at? Also would it work with any humidifier?

Ray · #9 04-25-2024, 02:58 PM

This is the "fog box" concept, using an ultrasonic transducer.

It will not "push" the fog well to the tank through a hose, so will need an exhaust fan on the tank to pull it up, but that accomplishes air movement and humidification at once.

Sure, as humidifier would push the air into the tank using it's own fan, but I'd expect less ability to control the flow.

SeraphSept · #10 04-25-2024, 10:34 PM

Quote:

Originally Posted by subtle_variegation

I recently purchased a used 18 x 18 x 24" Exo Terra terrarium for my small collection of (mostly) miniature orchids that I grow indoors. It holds some moisture after I water my plants but the increase in humidity doesn't last long (I'm currently using the mesh lid it came with and a small USB fan for ventilation). I'm looking for some cost-effective recommendations for something that allows me to keep the RH consistently higher.

From what I've read fogging systems are better than misters because the droplets are much smaller and therefore less likely to contribute to bacteria, mold, fungi, etc. However, I also know that the MistKing systems are pretty popular and have very fine mist.

I found someone selling one of their starter systems (I think it's the V4.0, not the newest one) for only $100 on Facebook Marketplace. That's probably the maximum I want to spend right now, if I could be closer to $50 that would be better. I'm a little suspicious of the cheap models on Amazon because of all the mixed customer reviews. I know I could buy one of those small desk humidifiers but I'd prefer something with more controls/automation (e.g. a timer).

Any suggestions would be greatly appreciated!

I think the best fix is to buy glass inserts (I would use glass instead of plexiglass, as plexiglass in my experience warps under humidity and heat) for your lid. I know of some who have glass strips cut so they can adjust the ventilation for simulating seasons and others who use pre-cut inserts that fit snugly over the screens (I would search 'glass top inserts for vivaria' or something similar). You can definitely add a misting system, and those two things together will do a lot to stabilise ambient humidity, but step one is slowing evaporation through lid.

I have used plastic wrap in a pinch while waiting for inserts to arrive.