Im a big fan of this stuff as a background, if you dont like it you can always peel it off, i agree with the black background to make the overflow less obtrusive. or relocate it to the far end of the tank.
You might look into trying to seal up the intake side of the wet/dry as best you can. this will keep the tank from degassing the c02. If you want to hide the c02 diffuser, stick it in front of the intake on your sump pump, this will pump all the micro bubbles into the tank still, and give them a lot more turbulence in the water to dissolve more efficiently.
The scape came out great btw!