Weird algae in fuge sump section

[jcs11236]

I set up a new sump a few weeks ago. The sump has a fuge section which I never ran before so I'm new to it. Got my led light and my cheato growing well. Only problem is that's it is getting this weird purple/black/grey color algae growing on wall and pvc pipe. I emptied the fuge and wipe it all. Comes off easily. But now it's coming back. Any idea what this could be. Never seen something like this.
It's only in this section of tank. No where in tank and no where in any other section of sump. There's lots of flow thru fuge. At first i thought that could be issue but don't think so

Any info would be helpful
Here's pic of the pvc pipe and back wall with the weird growth all over

 

[noelskii]

is that above that water level? molds?

 

[jcs11236]

That's all under water. A friend of mine said mold as well but don't know why or how.

 

[jcs11236]

Here's a pic of it all clean. Could it be the way the water feeds into the fuge?

 

[theMeat]

looks like purple-ish red slime (cyano), or diatom. Both can be purple. being where it is would guess cyano. It's in the fuge, no worries.
If you wanna know when you touch it red slime is well, slimy, and diatom kinda looks like it breaks up into powder.

 

[tsouth]

If it is cyano, careful not to let it spread to the main tank. This algae can take over if not cautious. Are you running any chemical media (Gfo/Carbon/etc?) Also what's your lighting situation and schedule for it?

 

[theMeat]

Cyano likes low flow areas. In the fuge low flow areas are good for plants to have time to absorb, and for pods to breed.