|I'll bet your lava lamp shows a much broader range of colours than we see here.
My idea for this challenge was not dissimiliar to this, but with a coloured light ball rather than a lava lamp. In the end I ditched all my shots and did not enter, much for the same reason that I don't think this will score high. Forgive me if I'm wrong, I'm only trying to help.
My ball glowed pink, red, orange and green, and yet when I shot it on 2 secs I could only ever get two of those colours showing, plus a large chunk of white. I'm not sure what the answer is, but perhaps some kind person with more experience would give advice for avoiding the problem another time.