A danger for using materials from the pond you found them in is that sticks, plants, etc, may be harboring predators or the eggs/young of predators. Make sure things are rinsed a few times and check frequently for any unwanted visitors.

We should also be clear on the kind of tadpoles you have. This section of the forum is actually a sub-forum for Dart-frogs and other wee exotic frogs. Advice for the care of dart tadpoles won't be quite the same as for our North American natives. Have you been able to identify your tadpoles?