Hi Dan,
I'm a
bit biased... but I love the Nimbus. And I think that Dry Ice
fog is one of the coolest effects in the world...
To your question(s)
The regular Nimbus will give you a nice, thick
effect for about 6 minutes that will
cover about 25'x25' (maybe a little more, depending on environmental conditions).
The Nimbus Jr will give you an equivalent
effect on about 10x10' or 15'15 area, but only for about 3 minutes. The Nimbus Jr is really suited to the "dancing on a cloud"
effect, for one song.
There are a few major considerations when you're working with a dry ice fogger.
1. Duration of
fog generation... this is dictated by the volume of water you're heating. Basically, once the water cools, your
effect goes kaput. So if all other conditions are the same, the Nimbus will create an
effect for a longer duration than the Nimbus Jr.
2. Duration of "Hang time"... this is dictated by environmental conditions, specifically humidity and temperature. Dry ice
fog is just water vapor. If the air is extremely dry, it vanishes quickly. If the air is humid, the
fog will last longer before it dissipates. To a lesser extent, temperature will
effect how long the
effect lasts. If you are using it from USC on a 20' deep
stage, it is will probably run off the front of the
stage into your pit before it dissipates, especially in NY in the summer. However, it will not
cover the entire
stage, wing-to-wing. You might (maybe) be able to
cover 20x40' evenly with an AquaFog 3300 (available from
City Theatrical)... but it will be more expensive, and require more
power than the Nimbus.
3. Volume... this is determined 2 ways (one way, really...with an inverse relationship):
Firstly by the surface area of the Dry Ice you use. As you lower the ice into the water (the nimbus has a few different settings for how low the
basket goes into the water), the surface area immediately sublimates. So, if you're breaking up your own bricks, the smaller the chunks and faster you submerge it, the more surface area you expose, so the faster it will react with the water, and the thicker your
fog will be.
Secondly, by the surface area of the Dry Ice (again). If you break up your dry ice into small bits, it turns immediately into
fog which gives you a huge burst, but the duration of the
effect will be shorter. If you want for your
effect to last longer, use larger chunks and/or do not dunk the
basket all the way into the water.
Basically, you will get a similar total volume of
fog...either all at once, or stretched out over time.
4. Coverage... this is both environmental, and mechanical. Basically, if you want to
cover a 40' wide
stage, you may want to use 2 of the larger machines (one from USL, one from USR). The water vapor will flow out of the machine (or the end of a dryer hose attached to the machine) with enough velocity to move it a fair distance, but probably not 40'. Trying to move the
fog across the entre width of the
stage with a fan will blow it up into the air, and make it dissipate more quickly. If you're happy with a thicker more localized
effect, using the single larger machine will give you the ability to get thicker
fog for longer in that area before your water cools off too much. Positioning the machine upstage center will
cover your space relatively evenly (depending on scenery and air currents), but will still probably not completely fill your
stage.
5. Heat-up time... Basically, these machines bring water up to near boiling. The Nimbus comes with an additional heating
element that can be powered from a SEPARATE 15amp
circuit. So, this machine can get up to temperature much more quickly than some of the competition, and faster than the Nimbus Jr.
In short, I'd suggest one of the Nimbus machines, to start. I don't think you'll be as happy with 2 of the Nimbus Jrs.
I hope this helps!
-Ford
