....
Welcome to the forum, Pauli
Rather than repeat loads of detailed info in this thread which duplicates stuff, hit the Search button and type in the words
catch tank and various threads will come up in which it's all discussed.
If there was just one thread I'd post you a link here but there are quite a few!
Recently there was a big Group Buy on the BSH version supplied by forum member Dubtek.
I hope this helps,
Robin