I'm not sure what a protein skimmer is, but I'm pretty sure that I'm supposed to put one in my saltwater tank. I imagine it skims protein, lol. We actually got one with the setup but it was confusing since it looked like the part where the electrical cord connects to the thing is supposed to be submerged underwater. Could that be right? Are they making devices these days where you are supposed to put the power cord under water? Growing up, I'd always been told that was a big no no! :shock: