too many bubbles coming out of skimmer

Question
QUESTION: I have a hang on venturi protein skimmer.  My tank is 120 Gal.  Its my first day with the Live Rock and I just turned on my skimmer.  In the collection cup there is a hole for air to be released.  So many bubbles come out of it and overflow after an hour or so.  Why does this happen and how can I stop it??????

ANSWER: hi, try adjusting the water flow through the skimmer, its probably too fast and needs slowing down. let me know what make the skimmer is and i may be able to help more.

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QUESTION: I have an Excalibur hang on.  Model HV2 for 200 Gallon tank.

Answer
hi, not a model we get here in the uk so unsure how it works exactly.

the bubble stop should greatly reduce the number of bubbles you get in the tank.

http://www.justphish.com/popup_image.php?pID=1406&osCsid=f248cbba66420b8593b0628

that is the only link i could find relating to that skimmer, just let me know if this is the 1 you have. but i am struggling to see where the water re-enters the tank.