is there anyway to take the pump out of the back of the bio cube ?

Just pull off the 90 degree elbow that connects to the return fitting (it is just a friction fit) and lift the pump with attached tubing out (after unplugging of course). If the suction feet are really stuck to the bottom you may have to reach in a wiggle the pump to get it to let go. I have a 14 biocube and this is how I remove mine for cleaning. Hop this helps.