best way for black back ground ?

  • We are currently upgrading MFK. thanks! -neo
Black Latex Paint.
apply it with a roller

i use it and vouch for it.
i use the store General Paint's brand.
cost me $13.50 for a 1L can plus the shake
 
If your tank's already set-up, painting the back is going to be a pita.. On my main tank, I spraypainted an existing background black, and it looks perfect.. If I don't like it, I can remove the pieces of tape holding it on.
 
i recommend latex paint since if you decide to change the tank or sell it, you can easily remove the paint
 
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