Hi guys, I'm looking into getting a protien skimmer and I'm a little confused. First off I have a 55 gallon tank with LR & LS. It has 6 Fish a few shrimp, snails and an arrow crab. I was wondering if I need a sump to use a protien skimmer or If I could use one just on the tank. After reading I'm still a little bit confused on what one to purchase and again if I need a sump. And lastly can anyone suggest a RO/DI system these brown algae spots don't look good haha. Thanks!