my pump is dying. I bought a $20 396gph pump last year and it is not pumping fast enough, it is causing the water to move very slowly in my tank. I am interested in this http://j.mp/1rNd5uS, but am not sure if it will be too big in my 250gal tank. I want to expand to some vertical grow towers over the winter and will need to be able to pump higher (this pump says it can do 20' high). What do you suggest.