If you want cheap, dry ice is the way to go. You really don't need a machine to do this. You can take a bowl of hot water, stick the dry ice in it and blow it away with a fan if you need something cheap and simple. Set up more of these for more fog, and it will stick to the ground. You can purchase dry ice in a lot of places, the 7-11 by our school even carries it, but you have to be 18 to buy it, at least in our state. I actually found a "ground fogger" at Costco Wholesale of all places for $40.00. They actually work fairly well, and it has a chamber in the front you put regular ice in, and a drain hose and container that comes out the back. When you don't want ground hugging fog, don't put the ice in. For the cost, the machine works nicely, I don't remember who makes it however, it is in our storage room at school.
This is because Hughesie knows that the site in question will have fully operational protection devices that will shut off the power long before one gets smoke... And because of liability issues no doubt...
This thing works, but its also helpful to get some quick dissipating fog. I get mine from rosco but there are other brands out there. Remember, any glycol based fog that you chill to help it sink will eventually rise, and stage lights only act as a catalyst. Quick dissipating fog is essential. For my school's production of Dracula, we used the quick stuff through the chiller in that link, and it only rose 2-3 feet before dissipating. Pretty impressive for a trashcan and some dryer hose.
your just not going to get the same effect with a glycol fogger as you would with dry ice, however if you already have a good fog machine (not the $20-40 kind you get at wal-mart or a party store) then the chiller with a quick dissipating fog isn't that pricey and will somewhat achieve the desired effect, however its going to take more juice, as the fog condenses when chilled.
it seems to me that most people that want low-lying fog are wanting the "dry-ice" effect, so for the price of building the chiller and buying the nice fluid, and ice/dry ice for the chiller, you could just buy dry ice and have a few buckets of how water and fans (as thelightingmancan suggested)
Hey Blevy first off welcome. Please stop in the new member forum and introduce yourself. We love to meet new members. Second, could you clarify if you have a chemical fogger already? I'm guessing the answer is no. What you need to do is build your own dry ice fogger.
The basic idea is you have a sealed container capable of holding boiling or nearly boiling hot water. You need a way to pour the hot water into the container and also drop in the dry ice when you are ready for the effect. You also need a way for the dry ice fog to exit.
An old cooler seems like an excellent choice for your container. If you do use a cooler seal up the drain valve really well with silicone. You don't want that thing leaking boiling water on stage. Open the valve squirt it full of silicone. Close the valve and just bury the inlet on the inside with tons of the stuff so there's no way the water's getting in there. Seal around the outside of the closed valve with silcone as well. Just find the small tube of "Silicone 2" at your local hardware store with the caulking and glues. The lid works great to keep it sealed but as an easy way to get in and drop the ice.
Now your way out. Get yourself some sort of flexible hose tubing. Something at least 2" in diameter... preferably 3" or 4" Home Depot again should be perfect. You need to cut a hole in the cooler ABOVE THE WATER LINE for this hose to come out. I would think about maybe getting a short solid piece of PVC pipe to use as the actual exit then have it turn into a flexible hose. You could actually do it all with solid PVC if that works for you. Depending on your setup you could just have 2' section of PVC sticking out the end and call it good. Your exit pipe needs to be well above the water line so that when you put the ice in and the water level rises you don't spill. Seal the area around your PVC/hose with more "Silicone 2". It'll dry pretty solid and hold it in place just fine.
Finally you need some sort of fan to blow the stuff out. You need to be careful about water and electricity here. I would get a 3" or 4" PVC Pipe 90 degree elbow and another foot or two of pipe. Cut a hole in the other end of the cooler again WELL ABOVE THE WATER LINE. Shove the elbow in the hole and point it up. Mount your other section on top of that. Mount a small desk fan to the top of your tube. It pushes the air down the tube across the water and out the other side. Make sure the upright extension tube and fan are out of the way so you can drop the dry ice in.
When it comes to putting the dry ice in, DON'T TOUCH IT!! Wear heavy leather gloves, kitchen oven mits, or welding gloves. It will probably come in large flat chunks that are about 1"-2" thick. PUT ON SAFETY GOGGLES and use a hammer to break it into pieces that are about 2x2... nice big over sized ice cubes. I always wear long sleeves as well. You do not want this stuff touching your skin! DO NOT PULVERIZE IT INTO TINY BITS... it will flash to gas too fast. IF you leave it one large piece it may dissolve slowly and sort of fizzle.
Finally purchasing. If you are under 18 you probably won't be allowed to buy it. I get it from my local grocery store meat market. Need help finding it in your area, try this website.
Dry ice isn't cheap but you need to buy several pounds to experiment. If you put too much dry ice into your machine you may freeze the water before it has a chance to do the effect. Same is true for if your water isn't hot enough. You need to experiment to get the effect just right. If you want to use it more than once in a show, be sure to dump out the old water and replace it with more hot water. Have a couple of giant catering style coffee pots running back stage.
Good luck. Be CAREFUL. You can get some nasty painful cold burns from the stuff. The fog itself can be dangerous as well. While it's not a big deal to breathe a little carbon dioxide, it is cold and heavier than normal air, thus it sinks and displaces the oxygen rich normal air around it. An actor who lays down in a fog might never get up again. Also make sure your orchestra pit doesn't fill with fog.
Now... dry ice... I can tell you that down here, the education department has a couple of volumes of chemical safetymanual that lists virtually every chemical you are likely to come across and the risks etc. associated with it and hence usage allowances - for instance, certain chemical are completely and utterly banned from schools, whereas others are suitable for years 11 & 12 only, others 7-12 and some boring ones K-12 and there are those which can only be used by specially trained teachers and there's one final category, chemicals which can be used by teachers and certain support staff for demonstrations. Now dry ice falls into that category. Ergo students are not allowed to handle it. Ever. I know it has the potential to be somewhat of a dampener on things, but it may be prudent to check you aren't setting yourselves up for a whole stack of issues with similar rules in your locations...
Food for thought... And Gaff, are you sure that you're not hitting 3K posts just because you post too much crap?
If you want to keep the water hot, you can also use an aquarium heater. You can get one for about $20.00 at a pet store, and it will keep the water about 90 degrees f. That will keep the water from freezing while you replace with more boiling water if you need it. You can use a computer fan instead of a desk fan, or even an inline inductor fan. You can get these at Home Depot, and they actually go in the 2 or 3 inch pipes for a HVACsystem. These actually work really well, and can handle a good bit of humidity. I think they are about $10.00, but I am not sure, and can be bought prewired with a plug, or you can wire it together easily. It might be easier to wire it yourself because they usually are not grounded, so you might want to ground the frame, it is next to water.
Never put a fan in the same hose that fog is routed through. With a dry ice fog, the only thing produced is CO2, so it might not be as much of a problem. But for future reference, any glycol based fog can gum up the fan blades and inner workings. Its always better to put a 'Y' joint on your pipe and use that fan to pump air in along with the fog.
yes i know that you're going for cheap fog, but i vote that cheap fog is the best way. we have two of the expensive fog machines and the ridiculous things break about every time we get them out of the box. we could save ourselves a lot of time, energy and money if we would just stick with dry ice and hot water. just so you know, don't think of it as the cheap way, think of it as the smart way