I have a prizm skimmer on my 45g fowlr tank. I think it does a great job, now. At first, until the skimmer was broken in (about two weeks for me) it did emit some micro bubbles. After that no bubbles at all, just alot of sludge
You have to adjust it a little at a time at first, but now no adjusting at all. I would reccomend it, especially on smaller tanks. HTH