I have a 5x2x2 (I think that is 130US gallons?). The inhabitants are a blond naso, a coral beauty and a lionfish (see signature for sizes). In addition are a number of lps (including an elegance that is a year old) and soft corals and on sps (green birdsnest).
The skimmer is performing great. I just got back from 26 days in the Indian Himalaya and my partner had emptied the collection vessel (a 6L plastic container) once and it was half full on my return.
I purchased the skimmer out of desperation. I would have gone with the 9015 (AS OVERKILL) but supply probs won out and this was the first avail (and my trip was comming up quickly) so I puchased the 9020.
The skimmer works. I feed the lion every two days (one whitebait - a fish the size of a sardiene), the coral beauty every two days (Hikari mega angel) and the nase sprungs green seaweed everyday.
The skimmer is quick to resume after cleaning and is easy to adjust.
Like all the Tunze equipment I have, the best recommendation I can give is - it works as advertised.
Grant