Only reason to have a PT macro is to notify your party of something. For example, if a WHM wants his/her party to gather at them they would make a PT macro for that. If what your saying has no importance to the rest of your party your flooding their chat logs of a possibly already flooded chat.
If you can achieve just as much with an echo than spamming party chat then you should consider to do so.
Try doing it the other way round. Blizzard > Water should make Fragmentation. Not only will the SC damage be higher, but you can then burst either thunder or aero, and aero V is your highest spell currently...
@Dasva and Seveth; You can't change gear without spellcast? I don't use it, and I almost never see my SC damage (on blu) unless I specifically don't change gear in order to do so.