PT6ER
Not so PT6ER. The water is not sucked up at all. There is a powerful pressure pump in the end of the proboscis. See earlier post.
But low will help as there is then less of a head to pump against.
Any suction pump at sea level will have to be very good to lift more that 20 feet or so as it will be getting too close to a vacuum.
For the same reason you can't maintain a syphon much over 20 ft.