I switched to Fluorite instead or black gravel for the substrate. I'd prefer to have healthy plants than pretty black gravel.
I tried out some lucky bamboo. But it didn't look quite right, and would have interfered with the Betta's swimming room.
I switched to more practical plant containers - 3 all the same size. I found that the tall glasses I first tried were unstable to siphon around.
So here's the final setup (for now) ready for a Betta.



I already picked out and ordered the Betta. He's a Red Dragon Butterfly Half Moon. Here's a pic from the breeder;

The Betta will be delivered on Tuesday next week. I've already chosen the name "Zhao Yun(赵云)" for him. Zhao Yun was one of the most skilled warriors and a very important General in the warring states period in ancient China (around 200 AD), and very handsome according to historical accounts. Zhao Yun is styled (like a nickname) "Zilong (子龙)" which loosely means dragon's son.
