student_cougar:
Should I choose a different pump? Are them some amplifier configurations that will allow me to run this pump off of the 2560? Should I use a completely different method altogether to agitate the water?
Even if you would get a 5V water pump (they do exist - I have a bag full of them) you can't power it off the Arduino board as its regulator just can't take the strain. You have to use a separate power supply for it - the power supply can be shared between the two but power to the pump must be split off before the Arduino board.