I just changed 20 percent of my water on Saturday, and now I noticed some foamy bubbles gathering around my bubbler. If I turn off the bubbler they go away. I just set this whole thing up with new filters and media on last Monday. It couldn't be time for a filter change already? The amonia and nitrate levels are fine. I wonder what is causing this. I have a penguin 330 filter in there. I'm sure there are some excess worms floating around in there.
Here found this bit of info on a web search:
Foam On Water Surface Foamy bubbles on surface of water. Protein breakdown from thrown slime coat, decaying fish and/or uneaten fish food. Use FOAM-OFF. If foam is not removed, fish may suffocate, since 90% of the oxygen transfer in water occurs at the surface of water.