We actually stopped using baby power on our daughter because it seems to promote rash.
Once the rash cleared up for the last time we don't ever see rash like we did before.
To clear the rash we rinsed her butt with water during diaper changes. We just put a towl under her and dripped warm water with a rag down the cracks, or if we had time we would run water over her butt over the tub.
To prevent rash now we do a daily air-out during one diaper change. I usually fasten her to her changing table and take 15 or so minutes to clean up her room, put her clean laundry away etc, while she airs out. She loves it.