You'll need to read on the subject on this link to understand my questions. It is long so, mainly concentrate on the "There are basically five different types of protein skimmer. These are:" subsection if you don't like reading.
AquaC - Protein Skimmers!
The questions are: What type of skimmer do you use? What size tank do you use it for? What type tank do you use it for? (fish only, fowlr, reef etc) Have you used other types before? If so, why'd you switch? How have the different types you've used worked for you? Do you recommend one type over another? Why or why not? In you're experience, has the type mattered? Would it be a good idea to have more than one type running at the same time or would this be money wasted? What do your co-aquarists think on the matter?