When I wash things like halters I put them in a pillow case. I use 1/2 the regular amount of soap and I usually only wash a few at a time. No overloading.
Be strong and courageous, and do the work. Don't be afraid or discouraged by the size of the task, for the Lord God, my God, is with you. He will not fail you or forsake you.
1 Chronicles 28:20