A little update: The big pink leather coral suffered a catastrophic meltdown, and fouled up the water in the emergency tank so bad that it looked like milk and smelled like rotten egg. It had grown twice as big compared to when I got it, so its a bit of a letdown. On the other hand, it had grown so big that it was towering over the entire left hand side of the aquarium, so I was actually planning on getting rid of it... not by killing it though
On the plus side, the zoanthids are opening up fully again, and the green star polyp is also opening up, albeit with significantly smaller polyps than before. The mushroom coral are not expanding much, but I guess they just need more time.
The plan now is to let the tank stabilize for a few weeks, replace some of the sand, and then figure out a new layout before forking out for some fresh coral.
Next time I'm gone for an extended time, I will:
* Place an extra heater in the main tank. Not sure why I didn't think of that before
* Double the size of the top-off reservoir
* Buy a new auto-feeder. Any recommendations?