I gave away my Red Sea Berlin, literally. Bit the bullet and got a Tunze...very glad I did. After a couple days of playing with air adjustment and skimmer level I can leave the thing alone till the next cleaning interval(I give it a good scrubbing and vinegar bath every 4 months). Pulls about 600ml of the dark stuff out a week on my 125g with a fairly heavy bio-load.
The Berlin worked OK on my 55g, but needed adjusting every few days to get dark skimmate. Tried the RIO2500 that came with it, a MAG 7 and an Eheim 1260 with the Eheim actually doing a very good job. I could reccomend the Berlin for a 55 with the Eheim for certain.