Ammonia is a natural waste product found in urine. It STINKS - our dry-pailed nappies the day of washing can bring tears to your eyes. I change DS every 3-4 hours, so I'd think 1-2 hours is enough, but we have bigger inserts than the typical bumgenius has (bumgenius is for going to nursery in or if he poos an hour before bathtime!).

A bladder infection would show as pain when urinating SOMETIMES, not typical sicky behaviour. But it would smell, and smell different to ammonia, which is pungent and sharp.