Dida 5gal water change this morning like I always do. Cleaned out the collection cup on my 9010. It's now about 7 hours later, and there's no skim in the collection cup. I opened the air intake screw 1 full turn hoping to see foam rising in the neck. The foam isn't even going half way up. Is this a problem? Or is this happening because of the water change? Lat week after the water change this didn't happen.