Hey! So I have this weird blackish thin algae that keeps growing. It grows it seems in the low flow spots but I have so much flow in my tank so idk how it’s possible. It can be starved out by light but once the light goes on it is back within a day. It doesn’t t look like cyano, it’s black and stringy and flowy. It first starts in the sand bed and kind of makes a mat and then slowly goes to the rock. I’ve tried Phosgard and GFO and nothing. Recently got a protein skimmer for my water box 20g so hoping that will work but can anyone help me? I’ll post pics when I get a chance