Talking about a bucket of pellets makes me think about giving way too much/many pellets or cubes.
Either will expand greatly after they are eaten, so there is a need to give only small amounts. Or soak thoroughly so you can judge the volume better.
Soaking in hot water expands them quicker than cold. I found that cubes finish soaking much sooner than pellets do.
I had to feed them to a gelding with a tumor in his mouth for a couple of months, so have some experience with them.
Cubes soaked up all they could of hot water in less than an hour.
Pellets would soak up a greater quantity of water, however, if then added more water would continue to expand.