They are pretty much essential for all marine tanks, whether you have corals or not. They strip out nitrogenous wastes from the the water. The bubbles are actually formed of the viscous, protein-rich waste, so when they pop, all that gunk collects in the cup and you can discard it. Brilliant!
I believe your skimmer may be too powerful for this tank. I honestly don't know what will happen. My skimmers are all in sumps, and they sit behind baffles away from the return pumps so there is some opportunity for the bubbles to dissipate. I suspect you will see a lot of bubbles. . .
Some people claim that you cannot over-skim, but skimming can remove trace elements, and in a reef tank, you may need to monitor these and replenish them more often if your skimmer is very effective.
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