As suggested by Edward, here is a video of Dawn Pro bubbles changing colour as they are inflated. I've made some improvements to the lighting so I hope it's satisfactory. The purpose is to identify the bubble size which is most representative of in vivo bubbles made with a tri-string loop. The position indicator on the right gives a measure of the bubble volumes. I'm no expert on colours so I'm looking for advice.

The mixes are all Dawn Pro/distilled water. pH was adjusted with HCl. 

Strength/pH for each bubble:

1) 40:1, pH not adjusted

2) 40:1, pH 7.6

3) 20:1, pH not adjusted

4) not used

5) 20:1, pH 7.6

6) 12:1, pH not adjusted

7) 12:1, pH 7.6

(ps: the bubbles start inflating when the position indicator is at 3cm. 12cm of displacement is equivalent to 1L of volume).

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