New tank w/ filter problem

Question
My boyfriend has a new table aquarium.  It functions as a table and sits on the floor.  The filter is internal.  It hangs on the inside and almost touches the bottom of the tank.  It has intermittently stopped or slowed filtration as we are trying to get it ready to add fish for the first time.  The first time it stopped working (small, spitty bubbles), he took it out, took it apart, and removed some of the carbon the original instructions told him to put in the filter when he set it up.  He thought maybe he wasn't supposed to use the entire package.  He reassembled it and put it back in the tank.  It began working correctly.  Within a week it stopped working again and the water is cloudy.  What is wrong here?  Is this a bad filter?  The instructions that came with the tank are now gone, so I can't refer to them.  PH is not even registering in the lowest color of basic.

Answer
Brandy,
without the brand name of the filter system I am sort of helpless here.
I will assume that the impeller is clear and that the unit does function as it should when it works.
You could delete the carbon as it is used up quickly and really does not do much for the tank unless you have a specific reason to have carbon it is not necessary.
Have you tested your water from the tap?
that could be the PH trouble as well.
What is the capacity of this system?
let me know on the questions and perhaps we can get a handle on this.
The worst case scenario is a different pump than what is there now or a new internal filter but lets see if we can fire this one up for now.