Awesome, thanks. I didn't know you could do that.
I already had this parameter set in the INI file to begin with. I'm not sure why it's rendering a background now as opposed to before. Maybe it's a floor plane? Though I had the floor turned off as well.
[edit]
I think in earlier versions of POV-Ray things worked this way. However, in POV-Ray 3.7 a declared background overrides the Output_Alpha parameter.
I already had this parameter set in the INI file to begin with. I'm not sure why it's rendering a background now as opposed to before. Maybe it's a floor plane? Though I had the floor turned off as well.
[edit]
I think in earlier versions of POV-Ray things worked this way. However, in POV-Ray 3.7 a declared background overrides the Output_Alpha parameter.