I had another go at another technique that I haven't tried before called 'dropping stuff into water'. Things I have learned:
1 - The glass container you are using should be clean. Photo's show up all your finger marks.
2 - Using something that is quite deep to drop things into is best.
3 - Don't keep dipping your hand in the water to retrieve the things you drop in it, it dirties the water.
So out of the 30 or so shots, I got one.