Nice.
First set of pools: on the square one I would suggest a more square dark area to show depth, vs. round. The round works great for the circle and pentagram. Regarding drop shadow, always looks better with one, but without allows other users to fit it anywhere. A drop shadow going away shows the pool creates a raised pool above the surface. A a drop shadow on top the rocks shows a sunken pool.

2nd Set: I like the fume one.