Looking pretty good there, Bushi!
I would say to try to use a little less wash less time, and maybe a darker one. It looks like you used a rust-colored one? Go light on rust shades, because they're easily overdone.
Try to go with a raw umber one, or even a tan colored one if you want to make the tank look dusty.You might even go for a "dust" one on the lower parts, and then a darker one on top?
For only your second tank though, you're definitely on the right track!