If this is your first time, I have to say that it is very well accomplished. Thumbs up!
The first photo tho, it isn't 100% sharp. I dont know the META-data for this shot, but you might just need slightly more power form the flash (which system do you use btw? Speedlights?), to achieve that.
Furthermore is the angle which the photo has been taken, a little to much, in my opinion. Maybe try go place the camera a little lower (like in photo no. 2), and get some kind og horizont as well.
The tones of the first photo is fine, but I wonder what the reflection in the water (in the middle) is? It looks like there are stones at the bottom of the aquarium-thing you used.
I would have removed that in post processing. (And used 'Liquify' to straightening the "tail from the drop" up.)
Last but not least; What method do you use to gain the drop? Is it by hand or have you made the classic "tube with a ball"-trick?
If you're doing this by hand, im very impressed.
But it would be nice to know some more about your setup and kit. Explaining to us what you have done, gives us better ways to help you making better and better work.
Have a nice day, sir.