Well theres a problem with your method.
Resizing a particle emitter doodad in the game will only change the rate and area they are dispersed, not the size of the particles themselves. Go in the editor, take the bubbles, resize them, and look at how utterly this failed. Along with this, I also increased their life span so they flow upwards instead of disspapearing within around .3 seconds.
I would import my model into your map if it's necessary and save yourself the time from the above experiment. Nice try though