This guy is exactly right, your rdruid us spamming red gems without the spirit to sustain his mana pool. Swap gems for Purified Shadow Pearl and hell never have mana problems again on top of providing a more powerful tree aura, boosting the heals output of every other healer in your raid for his group.
Super Mana pots and Dark Runes can cover any slack. Our rdruid is always one of our top healers and is never oom while also directing innervate on CD to the Arcane mages.