I just finished building my pond and waterfall. the waterfall flows out of the spill way fine but when it reaches the bottom, its not even and doesnt cover the entire width. it starts with a 14" spillway to about 21" wide area then drops to a 23" wide area then falls back into the pond. I'm using a 1600gph pump. should i be using a larger pump? any idea's how to solve this would be greatly appreciated! thanks in advance!