SuperThrive is brutal and can easily kill newly rooted clones, so its likely thats what did yours in if they didn't have roots. I don't water my clones at all, I just keep the dome moist. If you water whatever they are planted in (I use rockwool), the ends usually rot where the roots are supposed to grow. Plus, watering below soil won't do any good since there's nothing down there to water. You have to let the leaves work the magic until there are roots.