While I no longer own, or would recommend, a Berlin skimmer there are a few things I learned in my experience that I can share.
1. In order to eliminate any problem with the outlets making noise, thread in 3/4" pipe nipples and put tees on them. Insert a pipe in the bottom of the tee so that it is submerged in the sump water. This allows the water to flow out without creating a siphon but stifles the noise by letting it fall to water level in the pipe.
2. Use at least a Mag 7. Any lesser pump will underdrive the skimmer. I have heard of people removing the venturi that is installed on the Red Sea and replacing it with a 3/4" Kent venturi. Supposedly this will further increase the skimmer's efficiency, but I wasn't too fond of constantly having to tweak the air inlet.
The Red Sea Berlin is a marketing marvel, nothing more. It's not all that great a skimmer, but if it's on a smaller tank it should be adequate for reasonable stocking levels.
Hope that helps,
Scott