i had a Tunze 9004 in an RSM 250 I used to have. I liked it a lot. Solid, simple design. 2 things: there's a break in period of a week or so, and you might need to reposition in the water column. The "lift" of the skimmer is dependent on the height of the skimmer gate so you need to check its position after you remove the collection cup for cleaning, or more often if you dont run an ATO. Not a big deal...