Not very old, a few years ago I lost most of them when my town added zinc orthophosphate to my water supply just before I changed the water. In a few minutes, the corals and clams died. It didn't affect the fish and now I have resins specifically designed for that chemical.
Thanks Chris! The water is clear and that's my biggest exciting point today! There's always something though. What are the white dots that get on the back with the coralline? Are they coralline too?