Myself would not raise tadpoles in that type of set-up. I would use a seasoned aquarium according to tadpole size (5 to 10 gal. is OK for yours) filled around 1/4 of the height with dechlorinated tap water. An air driven matured foam filter will help reduce toxic ammonia and nitrites the tadpoles produce. Few live plants would help with that too and also provide security for tadpoles. With a seasoned filter you need to change 25% of the water once a week (with same temperature dechlorinated tap). If no filter; need to change 25% daily and it's more stressful to tadpoles.

Once they start getting all 4 legs you need to lower the water level. Then either slant the aquarium so there is a dry area or provide enough plants and a floating piece of cork so froglets can climb and get out of water if desired. Tadpoles can drown or dry-up at this stage. Best recommendation is to keep them in daily changed damp unprinted paper towel (use dechlorinated tap) for the first few weeks. If a water dish is used, try something very shallow (a lid?) filled with dechlorinated tap to frog's chin level and at least change daily.

You can feed food that is mouth size (same size as distance between frog eyes. In 3-4 weeks froglets will be ready to move into a half wet/half dry type enclosure. Hope this helps and good luck !