Those seem like legitimate settings. This is indeed a difficult problem since your skin type which I'm assuming is a Fitzpatrick 5 or 6 puts you at risk for hypopigmentation after any procedure. In order to accomodate patients with your skin-type, I use lower settings on the Pixel and have them return every 2 to 4 weeks. There is no data to support this but my fear of hypopigmentation (which most probably resolves) prevents me from doing a deeper burn. The problem is even more complicated since in order to give you a good result with your acne scars I would need to use a very deep penetrating burn (2300 long). Normally, with Fitzpatrick 1 or 2, I stack 6 pulses with 1 to 2 passes at 2300 long. In you, I would stack up to 3, 1 pass, at 1700 long but you would probably need 6-8 treatements.