I tried with dish soap and got white bubbles even though I had food coloring so that idea was out. I then moved on to other ideas. I settled on flour, water, and food coloring. I like the effect for the most part. I have to thicken up the "soup" a bit, add more coloring, and put a flex hose in it to spread the bubbles around the cauldron.
Is there anything else that you can think of I should try? Also what do you think so far? Thx for your help!