I have a 55gal with a corner overflow & a 20 gal sump underneath. I currently have one pump that pushes the water back up through the overflow. I had a second pump that pushed it over the opposite side of the tank through a U-tube over the top. I bought the whole setup used... both pumps were the same, but neither has a model, make, number, etc. on them. The second pump just quit working and I'd like to replace it because my tank had much better flow when I was running 2 pumps. Can anyone suggest a pump or GPH that I should be looking for when replacing this second pump? Thanks in advance!