Hey T-Rex,
First of all, it;s an impressive and ambitious effort. The scene is pretty well composed,but the elements outside of the two tanks themesleves could use a bit of work.
The groundwork is ok, but you need to invest a little time inlearning how to do vegetation more effectively. My first thought was "Where's the grass?!" A pondside scene would have tons of green vegetation-water is a great facilitator of growth, so you'd have vegetation everywhere.
Th water doesn't quite cut it, but you proably already know that. But having said that, I do commend you for taking the effort to try it. The best way to do muddy water is in layers--use epoxy type water, and use a thin wash of mud-colored brown in between three or four very thin layers.
You should paint ALL the crewmen--isn't that one on the fender without paint?
The tree looks out of place for two reasons--1., it's the ONLY one, and 2., it's the only piece of greeen vegetation in the scene! There should be MUCH more.
Welll, hey T-rex; it's a learning experience, right? And if you've made one that you feel is better than the last, then at least you're moving in the right direction, right?
Keep improving...