As per my discussion with Coralvue, the air draw goes up and the wattage goes down when you lower the water level. So based on your amperage readings I'd say your running a water level at the upper end of skimmers operating range.
I'll probably be buying one to try out before I jump in head first and buy 6!
here is the video of this skimmer and the exchange I had with Coralvue in the comments
https://www.youtube.com/watch?v=EnwBrD2_Leo