Funny, I was just about to come back here and reply to your last post but you've already come back for more!
With regards to the first: great idea, I don't know why I never got a background for this tank. I'll probably go with the obligatory white.
And the second: I'm excited to see this. To me, the 20-C is a perfect and unique size. There are a lot more 25 cm tanks (or tanks closer to that size) than 20 cm tanks. Plus, I'm a sucker for going as small as possible. Anyone who keeps up with my journals as much as you do should know that
I actually got three guppies for this tank while doing some Christmas shopping this evening. Nothing special, but I actually kind of like that. They're pretty assorted, and if (when, ha!) they breed, It'll be interesting to see what pops out. I'll probably post pics tomorrow.