algae in sump question

OK. Lately my sump is covered in red slime algae. The first section is free of it but my chaeto center section and return sections are nasty... The display is free of it besides the occasional algae on the sand from a flow dead spot. I know I'm kinda being picky but what would cause this? I light the chaeto with a 23 watt 5100k cfl. And have have dual overflows and a mag18 for flow thru the sump. I mostly am curious to get it cleaned up so I can store frags temporarily down there...any ideas? I know its a broad question but it's kinda odd to me its only in this one area...

 

Nevermind. I got it figured out.