Water change, and Xenia re-org

Performed a 2.5gal water change.

I was able to relocate two stalks by stuffing the attached algea into a hole in the top rock; hopefully this last until the stalks have a chance to attach to the rock.

Removed another pint of algea, mostly the brown kelp, mostly the remains of the clump that was the former home of the Xenia.

The last stalk still on the algea I moved to its now pinned against the top rock - hopefully it'll move onto the rock itself.