Often when importing objects they will look out of place because they have a different hue than the rest of the scene. When this happens you should color correct the imported object to fit with the rest of the scene by using a Curves Adjustment Layer or a Hue/Saturation Adjustment layer. There are no fixed recipes for this – the knowledge comes from lots of experience. In our case the water surface has a warm hue (yellow/red) while our scene has a more cold one (blue/cyan). By dragging the red curve down in the Curves Adjustment Layer I lowered the amount of red. Dragging the blue and green curve up increased the amount of blue/magenta thus making the surface blend nicely with the rest of the scene.