I agree, these skimmers MUST break in, while other skimmers work before the slime coat forms.
I wouldn't run it full blast, or you'll get to see why people hate the prizm's - they overflow the collection cup in under 15 mins if turned up too high.
You want the water level, where it changes from visible water to a mix of bubbles, just below the big O-ring where the collection cup attaches. About 1/8 to 1/4 below that o-ring is about perfect.
AS far as adjusting it...think of the adjustment knob like a clock face...never turn it more than 1 minute in either direction. the prism is sensitive...turning it up 5 minutes will look fine...but you'll overflow the collection cup.
Also, the prism has a tendancy to lose it's siphon....just pinch the airline until it regains the siphon. there's no need to ever put the airline on the closed 'siphone start' plug...just pinch it to stop the airflow so it can siphon.
good luck.