What is this junk?

[jostafew]

Hi everyone, I could use the help of a more experienced reefer. I've seen dinos, I've seen cyano, I've seen nuiscance algae, and I've seen this stuff (for longer than I would like). I'd appreciate some help IDing it so I can determine how best to deal with it. I know I have a phosphate problem, despite bleach and acid bath of nearly all my rock it's still leaching P at a stupid rate. I'm trying to get that under control and while I've halted growth of most algae and no visible cyano, this junk still proliferates. I clean it off the glass and within a day or two it's back and forms on all surfaces, where it's thicker it's a brown color. Slimy and stringy. Anybody know what I'm looking at?