That algae is getting MUCH better, thank you! It's all leftover from my last tank, and it's been dying off in hoards. Thank god.
ChemiPure is kinda like carbon. But better.
Those red things are not hydroids... They are SOME sort of polyp, they actually look a lot like the polyps that are symbiotic with sponges, but a different color. And without the sponge. My LFS guy picked them up scuba diving off the coast of Mexico (he has a license to bring stuff back) and had no idea what they were. I bought that rock for $10, didn't know what kind of lighting or feeding or anything they needed (neither did my LFS, it was kind of an experiment), but they have multiplied and done really well in my tank. They sure are pretty. I'll get a better picture later.