Oh I didn't see this earlier.
Passionate is good, being realistic is different unfortunately I saw way too many sick, stressed out, dying frogs. With them there is always a thin line between them being ok one day and almost dying the next. They are very unforgiving to husbandry mistakes and the younger, the more sensitive they are and unfortunately some breeders care only about money and not the wellbeing of their frogs, they sell frogs way too young, way too small. Add to it not perfect husbandry, stress ( moving from the store home, new too big tank, something else) and you see sad results. And the younger and smaller they are, the less experienced you are the more chances you see any problems until it's too late.

And as as I said earlier different rules apply to newbies and experienced folks. And mmmm I don't use hydrometers either but I do have most tanks on controllers.

And to to wrap it all - let's stay on the topic and let's try to help OP. It was very sad and frustrating experience for him and let's help him enjoy the hobby just like we do.