Hi Emma and thanks for answering questions. OK, that Gerber water might be great for pre 6 month infants; but appears it's not good for frogs. Recommend use tap treated with Seachem Prime (at aquarium section of pet shops) for all water needs. If your tap is hard water and stains glass, can use distilled for spraying; but avoid frog. If the mineral content of that baby water is too low or different from frog's needs it could affect how it's body functions (physiology).
Recommend replace substrate with new batch and mix it with dechlorinated tap. Have not use that brand but if same as Plantation Soil or EcoEarth should be fine. Mix it so it becomes slightly damp and clumps on fist but does not drip water out.
Good that you are using supplements now. Lack of CA can lead to Metabolic Bone Disease (MBD) and neurological issues due to mineral ion imbalance. Repashy and Rep-Cal products are highly rated. Here is some sample dusting schedules you can use: http://www.frogforum.net/food-feeder...schedules.html .
Need to bring the day temperature to 85F with a drop of up to 10F for night. Ventilation is important so keep vents open. Don't worry if humidity drops a bit and frog should handle OK between 50-65. Keeping frogs below their temperature requirements long term can cause kidney and lymph heart damage.
Hope this helps a bit and please let us know how frog respond to changes, good luck!