You should have to put some elbow grease into it because of the salt creep. Mine did not want to come off. I thought I was going to break it but I did not when I pulled it off. Also the little brackets will not come off without a screwdriver.
The hinge is attached directly to the tank, but the top just pulls off. Lift hood to 90 degrees like rasbora said and then pull up. You might have to wiggle it a little. If this doesn't work refer to rbredding's idea.