I noticed when I had saltwater that the more actinic lighting I used the higher my coralline algae would be. I know plants, corals, and algae use a lot of the blue spectrum to grow but I think coralline algae almost uses it exclusively, yellower lighting actually causing it to die or recede. As for the algae on your scrubber that's not coralline but I'm not so certain in the tank that its not. I noticed the same thing coralline grows at a higher rate/ sooner, faster on pvc piping.