I like how your scape makes this look substantially larger than a 20 long. BTW, where do you get your co2 filled? I'm not too far away.
It doesn't look that much bigger in real life. I have had tanks that actually look bigger so that's the only reason I say that. I do need to vacuum up some of the mulm I put in the tank though, I see it everyday so I didn't know how ugly it is until I see past pics.
As for CO2, I have been using Airgas in Concord forever. It used to be a bit of a trek for me when I was going to St. Mary's but now I am 2-3 min away, at most. I doubt it's the cheapest place but it only takes about 5 min and they have always treated me well.