Also, try soaking your diapers before washing them, especially if you are having a problem with urine residue. (babytooshy.com)
In high efficiency machines, the challenge can be that because the machines use very little water, you can actually have the hard water mineral deposits and urine residues build up in your fabrics, especially if your water isn't treated with a softening agent that keeps the minerals in the water — and the dirt! (thinking-about-cloth-diapers.com)