I use Amway too. My ex-bun used it so quickly that she can finished 1L in 1 week. After I told him time after time she couldn't useso much detergent and no improvement found. I bought the most expensive brand ( Amway 4L) and told her the bottle should use for at least 4 months. I can't imagine how much dtergent I take with the food when she wored for us. Now my maid use 1L bottle for a few months and the dishes are equally clean.