hmm.
Glass doesn't mix well with lightboxes. If you're going to be shooting glass, you'd be better off using striplights on the sides for seperation, specular lights through the liquid, and using a darker background. Darker backgrounds and strip lights make the glass clear and contrasty, getting that nice strip of light on the far sides of the glass, and that having an additional light at the back shining throguh the glass, towards you to give the liquid some body, the glass some seperation, and to make the liquid not look like a black abyss. As is, since this lightbox has a light background, you have poor seperation between the glass and the background on everything, for the exception of the liquid, which is just black.
You need to clean your sensor too, it's a bit dusty, and a little post-productioin could go a long way. The images from your camera are just the start of the pp process.