I personally think 24" is too far away for the stunners. I raised mine up to two feet, disconnected the white and UV -- not much penetration or color but just a little radiant glow from a green polyp acro and a green candycane. Wasn't impressive IMO at 24.
Mark, stunners are on a DIY all-in-one acrylic nano, 3.5 g, in my son's room.