A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Hi,
Andy Pope has done something very similar to this using Excel charts and it seems to me that the 'Simple' chart in this sample workbook may be what you want.
The chart in question is a thermomoter in the range 0% to 100% but that 0% to 100% could equally easily be your tank level.
You can download the workbook here.