dark red and purple acne marks do well with pulsed dye laser treatment or intense pulsed light treatment at a board certified dermatologists office. Acne is medical condition and acne scars are serious and spa treatments and home remedies dot really apply. Also it's best discussed in person with a board certified dermatologist as the verbal description over the Internet may not be accurate. There may be other lasers that could help.
Thank you for your question. There are a few different treatment options for dark spots from acne, also known as post-inflammatory hyperpigmentation. Different modalities include topical lightening creams such as hydroquinone, chemical peels, or laser treatments. The right treatment for you depends on your skin type, expectations, patience, downtime and cost. I highly recommend you consult with a board certified dermatologist or plastic surgeon to have your skin evaluated and to discuss treatment options that best suit your needs. Take care and good luck.