What the...??? Where's my mana?

[Irconfuzed]

Got my little bear tank to lvl 40 and I've noticed since about lvl 35 I'm hitting a mana potion as often as I hit taunt. I've got him at around 130 STR which is the requirement for equipment at that level and the rest in dex. Is it normal to blow through a whole bar of mana in the first two trash fights. I mean, my fun playing this toon has gone up in flames faster than Charlie Sheen's career. I never even log him on anymore....can anyone help?

Irconfuzed lvl 46 Pure Int Mage
Vindexor lvl 40 Bear Tank