There's a learning curve to cartotanks, just as there is for any different device that you use. There are a few ways to set them up, primarily in the way you prime the carto for the first time, which is the most important step in the process. I have another blog on cartotank setup which I use:
http://www.e-cigarette-forum.com/forum/blogs/comments/comment8704.html#comment8704
Here's another cartotank related blog that may be helpful:
http://www.e-cigarette-forum.com/forum/blogs/baditude/4830-8-tank-help-noob.html
Here's a review of the tank that I recommend:
http://www.e-cigarette-forum.com/forum/blogs/baditude/3318-3-ibtanked-pyrex-glass-tanks-review.html