I wish I knew the answer to that question as well. Most folks say use green or blue light as they are in the spectrum of crappie's eyes. I built my own light with 4 strips of green LEDs around a 1 by 1 inch plastic square tube and put it inside a larger clear plastic tube. It does attract minnows but I've yet to catch crappie using it. Maybe I was at the wrong spot or wrong time of year - or wrong something. I plan to use it more this year and maybe I can post a report on it sometime.