Hi,
In CVI the Tank indicator can include a numeric display to tell you the current value, if what you need is to have an extra slide to display the value you can create a separate slide indicator and every time you cahnge the value you update also the slide indicator.
If by the "non-filled bar display" you mean the line that separates the uper part of the tank with the lower part, then you can only change the color of this line, the width is fixed.
I may be out of line here, so please let me know if this helps.
Juan Carlos
National Instruments