Its been doing it for a month or so now. I just started getting annoyed at it, not very good looking. I have about 40 nassarius vibex, 2 tongan fighting conchs and a sand sifting sea star. The bubbles mostly just stay there and gather. Then I run something along the glass in the front just because it looks bad - and they float to the surface. There are also some green patches in the sand bed (down a little) and some red patches (down in the sandbed too). I also have what looks like hair thin spaghetti all around the sand bed that I can see through the front of the glass. Everything seems fine. All my snails are releasing "gambits" or whatever they are called and my nassarius are laying eggs on the glass. My dwarf Zebras are hanging out together (two by two) in little caves. My sand sifter has been in there for about 2 months and is still very active.