Protein skimmer or adding a bigger pump?

[brad.s1989]

I have a 94l marine tank, every time I did a water change about 3 days after it I would be getting a dirty tank (stuff on glass, water lookin discoloured). I asked the FS what was wrong an they told me to half the bag of media an replace the carbon with crushed live rock, an it's been ok since. I want to no if I would benefit from having a protein skimmer in there? I have heard mixed reviews? Some say the tank is to small to put one in, an I have heard people say you should always have one. I have also been told that replacing the circulations to a higher output pump is also good for filteration??

Can anyone give me any information
Thanks