I just bought a pretty decent 125-gallon setup secondhand and it was used for freshwater setup. He made a custom 55-gallon sump to go with it. But I have never had a tank with a sump in it before. It has a return pump and the sump itself but that's it. Will this type of sump work with a saltwater setup? I am pretty sure I will need a protein skimmer but any advice would be great!