Well, I don't have direct experience with it, so I can't honestly say it's garbage. What I do know is that it would be difficult for such a small skimmer to skim 75 gal
. The reaction chamber is limited since the bubbles don't have much time to gather the proper gunk, and the bubble volume is limited with a small diameter.
For example, my Euro Reef is 6" in diameter and 20" tall, and it's good for around 90. That skimmer is less than half the size of mine, yet it says it's good for 75 gal
. Since you have a 55 gal
tank, I would personally get a better skimmer... but until you really try it, you'll never find out.
Someone chime in if they've used it.