Berlin Classic Turbo skimmer ?'s

I just recently purchased my skimmer and I don't know if it is working or not but I just cleaned some scum out of the collecting cup. So I guess it is doing it's job afterall. My question is that there is no foam coming out the tube and into the collection cup. My pump is set on low because if I turn it up sudds will come out very fast and I will lose a lot of water so I set it low. The air tube is completly open if that help any.
Should I just let it run with the "wet" foam or keep it low?
 
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