Well that is a problem i have a moray eel and there escape artist so i have been keeping a plastic sheet over the top to keep it in and also let light in .. also you said you can get air saturation in the water from cold pipes ... what do you do to solve the problem when it comes to a watee change ?
Either allow the water to sit for an hour or two to allow the dissolved gasses to escape or just do smaller more frequent water changes in colder months.