Methinks AE's Simulate>Foam is just what the Doctor ordered, it's a powerful particle (bubbles) generator, with setting like:
Producer Point: Move to where you want the bubble produced
Production Rate: Drop to .085 or so (if you have a hard time getting small numbers with the slider, Right-Click the blue numbers, then click "Edit Value" and change the max to 0.5, then the slide will be set to a better range to choose small numbers)
Producer Y size (and X size): default .03, but zero make it one point
Size: 1 or 2 to taste
Initial Speed: 2 or so
Initial Direction: 90
The default Transparent bubbles are quite nice, love the wobble (also controllable) but there are many choices under Rendering>Bubble Texture if you want a different looking bubble. You can also control the Flow with a flow map, but bubbles being blow probably don't need that.