Soapnuts all the way. I use them for about four washes and they get the nappies clean. If there are bad stains I put them in the window so the sunlight can bleach them or hang them out.
Occasionally I put some baby oxi-clean from lakeland into the wash, which does lift stubborn stains. Some nappies stain more than others, my One life nappies seem to hold onto stains quite badly, more than my Motherese, not sure why.
Heidi