Skimmer Problem?

[wwidener]

I have the Biocube 32 with the standard Coralife protein skimmer in stage 1 as usual. I'm not sure if it is working properly. The chamber tube bubbles the way it is supposed to but does not foam. It simply bubbles as if air is blowing into it (obviously). No foam. No green water. ....or is my tank THAT clean?

Thanks for your help.

 

[Ludders]

Does it usually work? Had it been working okay before today?