Questions - Need some input

I recently purchased a used sump from an individual here locally. I needed a sump with smaller dimensions to fit below my 29 tall tank. (20 x 8 x 16) The previous owner liked this sump and swore it works great as is, however after mulling it over all night, I am begining to have reservations. As you can see in the included pics there are no chambers to the sump, just a sock holder and one giant area. He had the bottom filled with bio balls and the return pump attached externally. Everything I have ...