Berlin skimmer
 

Can anyone tell me anything about the Berlin turbo xl skimmer? Is this skimmer quality?

They work but you would be better off getting a Euro-Reef and no the berlin skimmers are not quality

They do work well, but after a while, they're hard to adjust, and almost impossible to clean!

My Opinion differs. At one time 90% of reef tanks ran that skimmer. In its day there wasn't anything better. Times change, and technology advances. It's not a great skimmer by todays standards, but there is certainly nothing wrong with it. They must have been built quite well, because there is still 1000's of them around.