Darrell, I think you should try the calibration procedure. Its somewhere here in the files section, as has been posted. Its not hard, you just enter the calib screen on the aladdin, using a default code. With the tank empty, you will see a value on the screen, that's the empty tank value. The numbers don't mean anything, its just a number the aladdin computer uses. Then you fill the tank and you will see another number, you enter this number and that is the 'full' tank value. I did see somewhere that you can use some value per mm of tank depth, rather than filling the tank. Easy enough and worth a try.