Using a fogger to increase humidity


I am a newby on the forum and arduino in general.
My interest is to develop a system to control and monitor a small green house I have at home using an Arduino Uno.

My question is pretty simple: I want to build up a fogger and found these elements:

can they be used directly on the Arduino board or are they just replacement parts?
On many other misters I noticed a controlboard.



Quite a few years ago I had a terrible experience with ultrasonic foggers. It did raise the humidity but it also left a whitish film all over everything. Never really looked too deeply into it, I figured it was the minerals in the well water that was carried by the tiny water droplets throughout the area. When the droplets evaporated they left behind their tiny payload. Normal evaporative humidifiers don't do this, they just release the water vapor and all the minerals and stuff stays behind on the plates or other medium as scale.

Thank you, I never considered that point.
Which arduino module would you then recommend to avoid such issue?

Misters for sure use too much power for an Arduino to supply, so you need some driver hardware in between.

As all you basically have to do is switch them on and off, get a mister that works on 5-12V, provide a proper power supply, and then use a MOSFET that in turn is controlled by he Arduino to switch it on and off.

Thank you, I never considered that point.
Which arduino module would you then recommend to avoid such issue?

Use distilled water?

If you have an enclosed green-house, you should have have rapid or huge changes of humidity.
by the nature of all the open exposed soils, your problem should be too much humidity.
however, if you make a PVC frame,
take a towel, and fold it once with a smaller PVC tube in it.
cut the top horizontal of the frame to allow you to slide in the tube and towel
then use a small pump to fill that channel .
the towel will offer huge surface area and act as a siphon to drain the upper reservoir of water.
this is similar to some home humidifiers.

the towel will get hard with calcium and all other deposits, but you can wash it.

A lot of small pumps for birdbaths come with caps to make a fountain spray.
that will also push water into the air and you will get more moisture in the air.

you can create a rock wall of cement and rocks, pump water to the top and let the water fall down the wall, the exposed water will have huge surface area.

if you have a garden hose and water from the tap, you can just use a solenoid and a mistor nozzle.

the beauty of humidity is that air wants the water and will help pull it out of everything it can.

A couple of things...

  • An ultrasonic mister doesn't create humidity. It makes water droplets. Humidity is water in a gaseous state... That is, humidity is actually "dry". However, the water droplets might evaporate faster than standing water, so they might increase the humidity faster (than standing water).

  • The droplets seem to be large/heavy. You can create "fog" over a pool or pond but even with a fan it doesn't spread-out very well. ...I tried to make a fog machine with a mister once (because it uses a lot less energy than a "real" fog machine) but once you put a fan on it and try to blow it around it just disappears. I assume if you let it go long enough the floor gets wet because the droplets are obviously falling-out of the air.

Thank you all for your answers,

dave-in-nj, your suggestion arose my curiosity but I have troubles visualising the setup.
Do you mean something like that :
I made a quick sketch