I looked up the professional ones to understand how they work and I don't see much than just an extra insulated container in the front where ice goes, and also a fan in the back helping the fog which apparently comes out from the left area on the back be blown to the front.
(warning, images are watermarked)
http://i.imgur.com/ck4SWsM.jpg
http://i.imgur.com/84SuFGG.jpg
http://i.imgur.com/LUNDsQt.jpg
http://i.imgur.com/O8v7t13.jpg
So I did an experiment by putting a polystyrene box almost the exact same size in front of my ordinary 1500W fogger, putting a fence 1/3rd from the bottom so ice wouldn't completely obstruct the fog's path (as in the real ones) and filled the whole box with ice.
My experiment didn't end up well. if I lower the fence which holds the ice, the fog stays on the ground but doesn't blow far enough to cover a decent area (creates only like 3 sq m), if I put it higher, it blows far enough, but the fog slowly goes up (isn't chilled enough).
I also tried getting rid of the fence and blowing the fog through the ice itself, but it obstructs too much and very little, 'more compressed' fog gets out and lays too low on the ground (few cm in height), rest of the fog gets trapped in the foam box in the gaps between the ice pieces.
I also experimented with the exit hole location and size, doesn't seem to change anything.
Does anyone whos done this himself have an idea what I'm missing? because I think right now to me my design is pretty similar to the commercial ones.