I have a 55 gallon tank with a built in filter. It has 3 areas in the back starting from left to right. First area holds water to flow into 2nd area where there is carbon balls and cotton cover the 3rd area is suppose to get water from the bottom of the 2nd area and shoot it into the tank. This is where its sucking air. Its suppose to get water from the bottom of the 2nd area and its not. Its only getting it from over flow from 2nd area. Anyone know what's going wrong here? My husband is at work I don't know much about tanks and I can't get ahold of him. I'm worried if it keeps not getting enough water it would burn out the pump