1. Press the button corresponding to the tank to be checked and release it, the display will show the levels in percent on the LED display. If no other button is pressed, the display shuts off after about 5 seconds.
2. If another button is pressed before 5 seconds, the display will immediately switch to show the new level or voltage. The 5 second time-out is restarted every time a button is pressed.
3. To continuously display a reading, press and release the desired button, and then press the same button a second time. When the button is released, the display will be on hold mode, which is indicated by the decimal point on the right hand side turning on. While the display is in the hold mode it will recheck the level once per second so the user can watch the level change while the tank is being filled or drained. The display will automatically shut off after 5 minutes in hold mode. To end the hold mode before the 5 minutes is up, press any tank button, and the display will shut off.