Growing in Sump. What is it?

[ChathamONCraig.]

What is this darker stuff growing in my sump? Good bad or indifferent?

90g display, up running for a year.
35g sump.
All parameters are within spec, but Ive lost a few lps recently and trying to figure out why.
This is the only weirdness I've found that I can't figure out. Spotted it while moving the chaeto around.

 

[Tahoe61]

If it's easily removed than cyanobacteria. If it's not easily brushed off, then it's likely coralline. I see green film algae as well.

 

[ChathamONCraig.]

Ok, thank you. I struggle getting flow through the sump, due to its weird design. Its an older Eschopps unit.