Summer crappie are famous for being slow to bite when it’s hot. They’ll bump a bait, nip it in the rear or just look at it. Summer is probably the most important season for using minnows because of the finicky bite.
A float is a good option for slowing down. It forces a fisherman to leave the bait longer than without a float. Toss the bait to the target, stop and wait, wait some more and then move it if no bite.
Make sure the float is balanced so a light bite is easy to see and the crappie doesn’t feel the resistance.