They don't need UVB and CA/D3 should be supplemented. Can use a 2.0 UVB for tank illumination (plants, observation) if needed. Whole bottom can be water, just need to feed crickets in bowl so they do not jump into water, wash off dustings, and drown. Here is a good read on White's: Frog Forum - White's Tree Frog Care - Litoria caerulea .