I love the coloring and shading!  That, plus the cracks with the water trickling out make it very eerie.  The graffiti plus the general run down condition make it feel like some futuristic utopian concept crumbling down to the corrupt reality.  As if it is a bad system coming fully into its own, just about to burst into full reality, letting all of the dark, sinister  secrets flood out like the water in the tank when it finally cracks, unleashing a new catastrophic reality onto all people, guilty and innocent.
 Keeping giant sharks in tanks for people to stand and watch without concept of fear is never a good idea.  
i love the bubbles, too!
  This is an overall excellent piece! ^^