Attached Link: http://www.renderosity.com/mod/gallery/index.php?image_id=434639

Problem is bubbles aren't normally round, use metaballs to create more realistic shaped bubbles and give them a glass or soap bubble texture.

Take a look at the metaball cavitation in this scene to see what I mean...

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Toolset: Blender, GIMP, Indigo Render, LuxRender, TopMod, Knotplot, Ivy Gen, Plant Studio.