I just received an Azoo sponge filter for me to use in my QT
. Well, it didn't come with instructions so I'm not sure how it works. I plugged an air pump to the small tube and bubble are coming out of the large tube (please see photo on website below). I though the bubbles were supposed to come out of the sponge-- right? I already did a search and can't find anything. Please help, thanks.