Great start!! In the first image try to keep the foreground in focus as the eye is always being pulled to the OOF coral on the left hand side.
Love the second image. You could set you black level to the darkest spot on the image...top right corner, then clean up the floating debris with a healing brush. What PP software are you using?
Like Hookup said, turn off those pumps.
Maybe just my eyes but I cant find a focus point in the third.
Great start. Tweak the WB a little, clean them up and watch your focusing.
Hope this helps