Finally, the tadpoles are starting to look a little bit different, and I can tell them apart now! The smallest one is slightly darker in color than the other two, and is much more active. The largest one is the lightest color and has the least developed hind legs. The middle one, well, is in between, but looks much more like the smallest one than the larger one.
The water is not stinking nearly as bad as it was last night, so I think I did the right thing. They are pooping, so they must be eating. I think I'll cut back on how much I feed them. The booklet says one level scoop every other day.