Mangroomer

I bought a mangroomer and it works pretty good but i think i got some ingrown hairs on my back. im not sure because i have acne. i use a buzzer with no attachment on my shoulders but i still get ingrowns even though it doesnt cut too close. is there a way i can continue to use the mangroomer without having it cut too close. i think at some angles it cuts close. i heard baby powder makes it so you can cut too close. is this true? can somebody recommend anything else?