Question for Wand Witches

I've been trying out a Power Siphon build, myself, lately. I've only gotten to about 25 or so, but I must say I have absolutely terrible mana problems. With just a "Lesser Multiple Projectiles" gem in Power Siphon, I run out of mana very quickly. Does anyone else have this problem? Does anyone have any tips for this? Does the problem eventually go away?

i have never tried this build but if you get a mana leach by % mod on gear or gem or passive would probably solve all your problems