Just dipped it in hydrogen peroxide but that doesn’t seem to help, and I noticed some red cyno I think should I dip it in chemiclean?If it was happy in that spot before then you're probably correct to rule out light/flow. If there is algea constantly touching the polyps then it will absolutely cause them to close up. I'd still strongly recommend getting at least some cheap test kits (not API) to test the more important parameters.