Welcome HeierFarm, remember to watch the ducklings every moment! They can get into such trouble left alone in water.
They may get tired after only a few minutes, so watch for that. The water needs to be about 90F, I kept the depth of the water no deeper than their bellies so they could stand up when tired. Make sure they return to a warm brooder, and if mine did not start preening right away I would wipe them dry with a washcloth.
There is a Sticky on Raising Ducklings, and Storey's Guide to Raising Ducks is a good resource.