protein skimmer

What kind of skimmer are you using and do you have any livestock in the tank? Also did you use tap or RO/DI water.
 
Depends. Firstnthere are usually still trace amount of oils left on the skimmer from the press mold. once the oil wears off it will become more efficient. If it's a new tank you should probably have a relatively light load, so you won't pick much up from them either. However within 1 - 2 weeks you will start getting build up from left over fish food and fish waste, and you will start seeing junk in your cup.
 
its a skerry aqua, and i currently use tap water saving for a ro/di system and yes lighty stocked 1 damsel, 2 clowns, 1 blenny, a urchin, and a goby
 
The bubbles put a small film of "suds" on the top of the water surface but it is still about 2-3 inches away from the top
 
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