i think i should have been more clear and yeah i hear you, there are so many information out there and a lot of people in a pet stores who pretend they know what they're doing.... we're getting here very angry once in a while after someone posting something what pet stores advised
anyhow
look, you need to get eco earth by zoomed or plantation soil by exo terra, expand with treated tap or spring water, take out all bigger pieces and use it for substrate. don't mix any moss in it, moss if ingested can cause impaction that i don't think you want to risk.
supplements- you need to use ca/vitd3 powder 2xweek and once a week multivitamin powder, but not on a same day.
would you have any pics of a frogs? what is their size exactly?