I have this problem too. Recently I started to think that maybe the thicker nappies and inserts, which Jake only wears at bedtime, aren't rinsing well enough. I don't notice the smell so much if I stuff a minki with a couple of blueberry inserts. If he wears a ll or a minki stuffed with a supersoaker, the ammonia smell is really strong. I've done strip washes and extra rinses too, and they seem to help a bit, but not for long.