If you can believe it I did this by squirting ink into a fish tank and then layering it in After Effects.
The devil is in the details. I layered it and darkened the blacks using curves. Then I added a luma key to drop out the black entirely. The ink was originally red and blue. I added a couple of keyframes using the change colour to effect to make it more dynamic. Near the end those effects are entirely playing with the light on set.
I borrowed and cleaned this cracked fish tank Ray had laying around. It needed a bit of love and a really good scrubbing. Then eventually I took multiple trips back and forth to the sink to fill it with super ice cold water and some bleach.
I made sure I had everything I needed close at hand. I set it up in front of the big black backdrop I previously painted. I put some buckets under the folding table to fortify it in case it collapsed under the weight of the water. I had extra towels ready since it leaks a bit. I set up my Canon DSLR to take HD video and got deeper than my elbows into the special effects photography.
To light particles in air or water you must have a hard light source coming from the rear. This is 3/4 cross lit from the back at a high angle. When I get my camera set up just right you cant tell it is a tank full of water. I'm not going to give away everything I shot or how it will be used yet until my project is further along. A guy's got to keep some mystery :)
Needless to say, I am very happy with how it turned out, it went better
than I expected though it took a lot longer than I anticipated. This is the part that really slows down the process, filling and draining the big tank of water. I'm glad I selected the smaller tank. The bigger one would have taken forever to fill and drain. I still have to shoot another session with this set up in the next few weeks for some additional elements like smoke and fire. I cant wait.