This isn't a support question...its a "are druids bad for mana management" question?
As soon as you hit 550+ item level mana should never be an issue for Druids ever...
Between 500 to 540 mana will be tight so look for routines that have mana saving options.
Tips:
Don't use Wild Growth - This is should only be used in emergency healing large grounds.
Don't place Wild Mushrooms - This again should only be used for large healing.
Both of the spells above cost a very large amount of mana, so if your routine is spamming them then you need to adjust the settings.
I have HM 7/7 HC & BRF 10/10 HC ( Correction, had!)
You must have something set wrong or your raid is taking far to much damage as I could clear Blackhand HC and still have 20%'ish mana left.I have a new 679 drood wich i've leveled it on 2 weeks. I have some mana issue to on fights like Blackhand HC, i'm oom on P3 if I don't use mana potions (and 34k mana is not enought). You should have Darmac and Blackhand (with Sanitizing) to be fine
My old drood (before the waveban) had 687 and i had no mana issues...