Also on topic: Marks of water would give random nymphs wouldn't they? Since marks count as other cards. It wouldn't be all water nymphs, and that would reduce the effectiveness since there's no SoR to make use of other nymphs' abilities.
Yea marks create random nymphs when targeted with tears, also they would have to be upped marks, since unupped ones stack on the mark slot becoming untargetable.
Even if someone has 6 upped water marks (I doubt), for a tears/randomness/SoR deck IMO it is more effective to use QT for paying the shards and sometimes using non-zero cost abilities.