Re: pointers on how to deal with ammonia. please.
I wouldn't expose the diapers to hot water without soap in there, it sets things in.
I have a personal vendetta against Tide, and have to use Country Save to avoid ammonia problems, but to be a little more fair I can suggest putting vinegar in your rinse, to strip out the stuff Tide leaves on diapers (the optical brighteners and so on, which can also help yuck stay in the diaper). With soft water, you may very very very likely be getting detergent buildup.
Here's what I'd try ...
Rinse & ring out night diaper
Dry pail with the lid cracked (getting oxygen to the diapers slows ammonia development)
Cold rinse with baking soda, no need to soak
Hot wash with Tide if you must, but preferably a buildup free mainstream detergent (Like Biokleen or Country Save)
Cold Rinse with Vinegar
A soak in washing soda, or adding washing soda to your wash, helps strip out ammonia but it's yet another thing for your soft water to fight to rinse out.
Another choice is having a night diaper that has many thin flaps of fabric and mostly natural fibers, because they come clean more easily.