[Tiger15]

Does look like Spyrogyra, green thread algae. You can physically remove it with a brush, and it will come out in long silky chunk. You can physically remove it or dose with API Algaecide if you don’t mind killing invertebrates. Hard to get rid of as no algae eaters eat it, and thrive in the same conditions as green plant.

 

[Tiger15]

The only inverts I have are snails, but Algaecide will kill them too? Do Amanos not eat this stuff either?

I have not tried Algaecide to prove it will kill snails, but the label says don’t use with inverts. Amano will not eat spirogyra.