don't throw it away it just need to be put together right some little thing might be missing, or in the wrong place check here to see if you got everything and then try it again, if the lid isn't fit into the groove right it will leak try this
http://www.marineandreef.com/v/vspfiles/pdf/magnum_manual.pdf
http://www.marineandreef.com/v/vspfiles/pdf/magnum_manual.pdf