Actually, so i get soem gas buildup at the end of the day. I purged the system before i went to sleep and this morning i noticed there was still some buildup of gas (no i dont run co2 at night). I am thinking since i use a TOM's surface skimmer, it must be drawing in air which gets trapped due to its low solubility in water. Any ideas what i can do to alleviate this? Thanks!