I feel like I'm always the last to "know," as in "who knew THAT?" I just today heard of washing machine detergent strips and sheets. Does anyone use them instead of Costco (or other) detergent jugs? If so, has anyone figured out the cost per load? Do they get the clothes clean without damaging the washer in any way? I found one brand through Amazon, but someone said it was made in China. I'd prefer to use American-made if possible.