PS paint. Try to get fresh and powerfull water mood in here.
Edit: This is free to download and use for everyone.
(sait uuden fanin...)
Did you use a mix of textures and brush strokes or it was all pure painting?
You did a great stock image. I'm sure it will be useful to many artists here. I'm already imagining hundreds of things that could be done with this beautiful background.
Congratulations! Keep it up!