Hi Matt, thank you for your comments. Well spotted!!
The specks are from some black paper that I put underneath the glass. At the moment I only have clear glass and that wasn't working so I decided to put some black paper underneath and I think what you can see are the flecks on the paper!
I'm hopefully going for a trip to Ikea tomorrow night to look for a black table top glass, I believe they also do it blue and green as well, which should give a cleaner surface but I might have a go at cleaning this one as well!
How are the water drops going, I'm hoping to have another go again this weekend!