Water Only Fog Machine (No Dry Ice, No Fog Juice)





Introduction: Water Only Fog Machine (No Dry Ice, No Fog Juice)

About: There are some things you should just never, never, do...

Water Only Fog Machine

Everybody loves fog, Theatrical Fog that is - Especially at Halloween, and there are many ways to make it:

1. Dry Ice was my first introduction to fog - Dry Ice dropped into hot water provided LOTS of dense low-lying fog. It was great, but you had to go get the dry ice and be very careful handling it. When I lived in San Jose, California there was a company called Able Carbonic near the airport that had a Dry Ice Drive Through around Halloween - it was great!. You could pull your car right into their warehouse and purchase however much dry ice you wanted without leaving your car.I've built a couple of contraptions to make using dry ice fog easier.

A safety note - Dry Ice is Carbon Dioxide and in addition to being extremely cold (-109.3°F or -78.5°C), causing instant cold 'burns' on contact (use insulated gloves), it can present a suffocation hazard because the carbon dioxide gas evaporating off of it will displace the normal air around you and deprive you of oxygen. I once had a small room filled with dry ice fog and it became apparent by the coughing and faster breathing that there was too much carbon dioxide in the room - Exit NOW if you find yourself in such circumstances!

2. Heated 'Fog Machines' that heat glycol-based or glycerin-based 'Fog Juice' to spray out a plume of white smoke/fog. I like to think of these as smoke machines more than fog machines. These are used at concerts to make the beams of light/lasers show up, and traditional low lying fog too . My commercial photographer friend introduced me to this type of 'fog' machine. He had a professional Rosco unit that was really built like a tank and pumped out tons of smoke. I eventually purchased a Rosco unit and have since purchased consumer 'fog machines' of various sizes at big box retailers on clearance after Halloween so that now I have 3 (or more, not really sure how many I have ;-).

'Fog Machine' fog tends to disperse all around you as if in a London Fog, so if you want it to hang near the ground you have to chill it. There are tons of Insturctables how to build one of these fog chillers.

3. Here is the new fog method - Ultrasonic Atomization. This is where a piezoelectric disk is electrically pulsed to vibrate at ultrasonic frequencies with a shallow layer of water over it. The surface of the water breaks up into fine droplets; fog. Ultrasonic humidifiers use this method to produce the visible mist being blown out of them. Many years ago I saw the fog potential of ultrasonic humidifiers and 'plumbed' the output of one of them via a hose into a jack-o-lantern to have fog creeping out of its mouth.

Fast forward to today. You can get high capacity pond foggers that will produce large amounts of fog (using >2 liters of water an hour). These high output atomizers are not cheap (~$200) but dump out tons of fog, low lying fog, without any carbon dioxide gas. No consumables but water and electricity!

Step 1: Materials

You will need:

5 gallon bucket and lid

4 inch diameter dryer duct (larger diameter is OK)

Computer cooling fan and matching voltage plug-in AC adapter

Machine screws and nuts to fasten fan in place

Empty 2-liter soda bottle

One 12 Gauge steel wire (a T-bar ceiling hanger wire works)

12-Jet Ultrasonic Water Vaporizer (Mister) and associated power supply

Remote Controlled AC switch (optional)

Heat-shrink tubing or electrical tape

Solder (optional)


Frozen Ice packs or Water Ice (as opposed to dry ice)



Drill Motor and Drill Bits

Utility Knife or Sabre Saw

Wire strippers

Soldering iron (optional)

Heat gun (optional)

Step 2: Cut Some Holes in the Lid

Take the bucket lid and mark out locations for the fan (main opening plus mounting holes), dryer duct and also a hole for the power connector of the atomizer to pass through the bucket lid.

Cut out the openings using a utility knife or sabre saw. Cut the duct opening about a 1/4" smaller in diameter than marked so the spiral duct will fit snugly in the hole.

Step 3: Prep the Fan

Cut off the end of the cord of the Plug-in AC adapter and strip the wires bare. Connect the stripped AC power supply lead wires to the fan leads. Match the polarity (+) to (+), (-) to (-). if they don't have matching colors you may have to use a voltmeter to determine polarity or just go with trial and error.

You can solder or just twist the wires and use heat shrink tubing over the connection or just electrical tape.

Step 4: Mount the Fan and Duct to the Lid

Use machine screws, nuts and washers to fasten the fan to the top of the bucket lid with the airflow into the bucket. Since the duct is the spiral type it can just be twisted 'into' the opening to fasten it in place.

Step 5: Set the Atomizer Head in the Bucket

Place the atomizer into the bucket, threading the power cable up though the hole in the bucket lid cut for the connector. After the cable is through the lid pack the connector opening with some foam to seal it off. Alternately you could cover the opening with duct tape.

Add water to the bucket until the level is per the operating instructions or until the 'low water' sensor is just covered.

Step 6: Auto Fill

To keep the fog machine operating continuously the water needs to be replenished. An inverted 2-liter soda bottle will do the trick. It acts like the 5 gallon jug on top of a water cooler (bubbler).

Bend a wire support frame out of 12 gauge wire and hold the bottle in place with a zip tie. Bend a upside down U'-shaped hook in the top of the wire. Select the length of wire above the top of the bottle so that the mouth of the bottle is at the water level you want to maintain.

Cut a slot in the top of the bucket lid so that the 'u' bent hook can fit through. Position the hook so that moving it to one side will catch on the lid and suspend the bottle. Fill the bottle with water and hang it in position.

Step 7: Energize!!!!!

Power up the atomizer. You can watch it work and fill the bucket partly with fog. The fog will not overflow the bucket, it just settles into the bottom of the bucket. Any fog moving up toward the lip of the bucket just evaporates before it goes over it. Air movement is needed to get the fog expanding and billowing. Power up the computer fan. You should now have fog pouring out of the duct!

If you want you can plug the atomizer power supply and fan power supply into a remote controlled switch. That way you have fog on demand!

The atomizer is using about 300W of power to atomize the water into fog and a large portion of that will go into the water as heat. So in order to keep the submerged atomizer from overheating you will have either run it for very short periods of time or add frozen ice packs or even just frozen water ice to keep the water temperature (and the atomizer) cool.

Now you have a virtually unlimited supply of fog - so put it to good use, like one of my favorites; a bubbling cauldron - but that's an Instructable for another day!


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43 Discussions

Do you know where to buy a cheap 12-Jet Ultrasonic Water Vaporizer?

2 replies

As mentioned in the Instructable, there really isn't any "cheap" 12 -jet vaporizers. Amazon carries one similar to the one I used but it is about $200.

I found a 3 jet unit that is rated to put out 1.2+ liters per hour. Sounds too good to be true for $41. I have not tried it but plan to in the near future.

Thanks for the suggestion!

Just ordered this, will test it whenever it arrives from China, but only $8 so a smaller upfront investment!


1 reply

Thanks for the comment and glad you are interested in exploring the use of ultrasonics for fog. However, a unit like the one you sent the link to will not produce enough atomized moisture to produce fog that you can blow into a space. If you are lucky you should be able to fill a container with a small amount of fog. Which might be OK if you want to create a mini cauldron filled with fog.

Good luck - let me know the outcome.

I definitely want to make this just curious how your original is holding up or if it wore out (like my plasma globe did). Wanted to see if you think it's still worth the $200 before I spent it.

At my work we go big with Halloween decorating but I've never been able to use a fog machine (and don't want to hassle with dry ice) since mine is a heated that will rise and set off smoke detectors. I definitely want to have one of these in my effects collection for next year.

Great job this is awesome!

7 replies


The ultrasonic vaporizer/atomizer is not cheap so I understand your concern in spending the 'big bucks'. However, I really like my unit. There is nothing quite like tons of billowing fog on demand. And I like not having to go get dry ice or having to keep feeding dry ice into a unit - This is so much nicer. I do have to use water ice to keep it cool, but that is so much easier.

I've had my ultrasonic atomizer for about 5 years - Now I don't use each year and I don't run it for days on end, but it seems to have held up well. The piezo disks on the unit are replaceable and my understanding is that it is the disks that wear out or fail.

If you are going to build this fogger I would make two suggestions: 1) Use a larger container. I put it in a bucket to enter the 'bucket challenge'. I usually have mine in a larger container that I can wheel around with a sealed flip-up lid that works great. 2) Get the float ring for the atomizer. The float holds the atomizer at the correct water level while floating on the top of the water. This way you don't have to have a water auto fill device, the unit just floats on the water. This allows for a larger supply of water for longer run times and more water ice to keep it cool.

Sweet! I was going to ask what improvements you would suggest. I already bought everything and was going to build this weekend. My fogger came with a float but obviously doesn't fit in the home depot bucket. Are you suggesting a cheap cooler? Or what exactly are you using? I read the same about the disks and it has great reviews on amazon so I just bought it. Totally awesome idea! II'm going to test it buy fogging my backyard lol.

Thanks again!

I used a type of rolling storage container. I don't remember if it was general storage or for dry pet food or something similar. It has a nice gasket in the lid so all the fog goes out the hose. See the photos:

Good Luck on the build. Let me know how it goes and send photos!


I did your exact same setup using a 50lb pet food container except I fitted the hose into the container like you did with the bucket (the adapter I bought was too big but I plan on returning it for one that fits)
and I used gorilla duct tape to seal everything for this test run. Looks great after it runs for a bit. Any advice for thicker fog? Thanks a lot! This is super cool!

I forgot to say my fog does not look like yours does in the kitchen photo.

Fog thickness has a lot to do with the amount of air mixed in and also ambient humidity. I had one set up that had a disk pivoting on one of the fan mounting screws that could be rotated to partially close off the fan opening to reduce the air flow and increase the fog density. You can also run the fan at a lower voltage than what it is rated (12V run at 6V; some will work, some will not at half voltage), which will reduce the air flow. If the air is very dry a greater portion of fog will evaporate... If you are inside, as ambient humidity increases, the amount of fog that 'hangs around' (pun intended) should increase. Good Luck - Please post some photos when you get a chance under an 'I Made It!'. Thanks!

Dr. dB

2 years ago

GREAT idea!

And, you and other respondents below are quite right - many of the "traditional" stage-fog formulations are, at best, unpleasant to breath after awhile (...and, I often fog LARGE stages, both indoors and out, as part of my job in Entertainment Engineering.)

The mildest we've found, so far, is from an outfit called "HaseBase" - mostly water, very little in the way of "adulterants", and with hardly any "nose" to it - but even THAT can still be a little rough on sensitive humans, if the concentration gets high enough, over extended exposure times.

The only thing your approach could possibly do is deposit a little re-condensing water onto nearby stuff and, considering how many times each year we and our gear get torrentially-rained-upon, anyway, I don't see that as a disadvantage at all! (...except for possible slippery spots on a well-waxed dance floor).

Certainly in autumn, at least, (Yay, Hallowe'en!), the overall humidity should be low enough for that to be a problem only in very small spaces. (...speaking strictly for the Temperate Zone of the Northern Hemisphere, of course!)

One question, some suggestions:

Does the "spec plate" on that pond element's power supply say 20VDC? Can't quite make it out... If so, a 317 regulator transistor or a 24V fan, and you could split it off the same DC line, reducing your parts count by one wall-wart.

I would recommend soldering the "inside" connections, then brushing-on some "liquid electrical tape" - makes completely water-tight joints in short order.

Also, imagine if one could find a small, dead shop-vac, instead of a bucket? Wiring, holes and hose(s) already ready already... just have to swap-in the right fan and re-connectorize. Plus, lots of interesting outlet-nozzle-shape options!

At any rate, well done!

6 replies

Thanks for your comment. I like your shop vacuum idea!

The power supply for the atomizer outputs 36Vac so tapping off would require a little bit more circuitry than if it were a lower voltage DC.

Whew! That IS a bit steep - even though it's still within the ratings of an LM317, that would certainly turn a 7800-series reg into an S.E.D. (smoke-emitting device)! Easier to just stick with the wall-wart, after all... (And I can't think of any (cheap!) 36V fans, offhand.)

OOH! Just expanded the shop-vac idea, though - a (cheap! used!) WORKING "wet-or-dry" one, with a small Variac or triac motor-speed controller to ramp-down its own, original blower's output...! Internal electrics should already be fairly waterproofed, etc...

Some even have "drain plugs" near the bottom - reversed as a water inlet? ...float-switch/valve? ...or am I getting TOO absurdly complicated, now?

36 volts AC. So the direct to voltage regulator concept is out.

I think that you would not use the shop vac's motor since it would be pulling air in the hose instead of having fog come out of it. But I still think this is a great starting point for more development.

some smaller shop vacs models have both an inlet port and outlet port effectively turning them into a blower depending on where you plug in the hose

but the rapid air flow would dissipate the fog too quickly and spread it out faster killing the effect

Yeah, it would have to include a bridge rectifier + a handful of support components, circuit board, case (waterproofed, if built inside, near the fan), and, thus, MUCH easier your original way, with an off-the-shelf, Mains-powered wall-wart.

Most "upright-tank-style" shop-vacs (in the U.S., anyway), even the "teensy" ones, have identical fittings on both the inlet and the outlet, allowing the hose to be attached either way. However, unlike your design, which PUSHES (relatively) clean, outside air into the bucket to eject the fog, the original vac motor would end up SUCKING the moisture through the fan & motor constantly, which might not be the greatest thing for wiring, bushings, etc. (Certainly doesn't do wonders for the fans I sometimes "rescue" from being directly in our stage-haze-streams - even with the nicer, "HazeBase" brand stuff, a bit of "goo" still condenses all over the blades, motor, everything... ...almost always have to admonish the "new kids" at least once to put the fan BEHIND the hazer, or they get to clean it up themselves!)