I made the hanging rock by supergluing lava rocks together, then gluing this to a piece of clear acrylic that I had bent into a hook shape to hang on the edge of the glass (a toaster oven will make the acrylic flexible till it cools). It's held up really well so far and lets me reposition it as needed.
The substrate is oolitic aragonite sand that was very thoroughly rinsed.
In the middle of the summer the tanks started developing what I believe to be cyanobacteria mats all over the rocks and algae, covering everything with a web of stringy muck that trapped air bubbles all over and was quite ugly. Unfortunately I don't have many pictures of the tank during this time, but there's one below that shows a bit of what it was like. I ended up getting some Ultralife Blue Green Slime Stain Remover and mixing a little in at a time (no more than 1/4 strength of what they recommend on the package, and always letting it dissolve in a bit of water I pulled out before pouring it back in, then swirling the water in the tank). I did this probably 3 times in 3 weeks, each time seeing the cyano turn more brown and start to dissolve in the water. After about a month it was completely clear. I did do a ~25% water change after this to clear the water a bit. The shrimp are more active now that the cyano is gone.
Excitingly, during this time when I was treating the tank, I started finding jellyfish! They must have come in the water that the shrimp were shipped in, as I know Vorteil has had some in the past. Though it took them over 4 months for them to become visible (April to July), so I'm guessing they were living as "spores" or whatever jellyfish are when they're first born. They never grow bigger than a 1/4" (for the main body, the largest ones are a little smaller than a quarter with the tentacles all spread out), but I currently have 3-4 this size with many more smaller ones, so they seem to be doing well. The smallest I've seen are quite literally the size of a grain of sand. Incredibly tiny, they're almost impossible to see. It's also tough to see them, as they mostly sink down to the white aragonite and blend in. They seem to be primarily light reactive, as when I switch my light from daylight to blue light some of them swim to the surface. Thus, I don't really know how many I have in the tank, but I'd estimate 20+ amongst the different sizes/stages of growth (most I've seen at once was 8).
I also rearranged the fake bush to be more towards the back corner, the chaeto became too much in the way once it started growing/filling in. I have actually trimmed it back twice now, grows pretty fast.
I've only recently started to see berried shrimp, but the first only had 3 eggs which she dropped, and the second had more eggs but ended up dropping them all too. I'm hoping they were just inexperienced mothers and not something with the tank.
Tank as it looked last month:
Spider that crawled into the tank that the shrimp ate, background also shows a bit of the cyano mats covering everything: