If you're having mana problems, you could Time Dilate your Luminiferous Aether in order to get 30 sec of refresh (not sure if it's possible, I'm personally only lv31 in the class), and you should make sure you're in Nocturnal Sect when you're only needing to heal the tank. Diurnal Sect is really only good if you're pre-50 or if there's a consistent hp drain on the entire group.