there may be a problem once they get bigger. the problem would likely be that they would overcrowd the pond and devoid it of algae..thus the tadpoles would start to die in large numbers from starvation. my suggestion is to get 1 or 2 predatory fis that are big enough to eat the tadpoles..and see if that reduces there numbers any. if that dosnt work ..you may want to start removing the tadpoles yourself.