Mold and fungus are hard things to deal with. When we did indoor winter gardening there were fans going all the time to help move the air around to prevent this. I have never done it in an aquarium but having fans going is a good idea. You know seriously have you ever looked into some books on indoor growing of Marijuana. While i know your not growing it, or maybe you are
they do have the whole indoor growing nailed down to a science. There are several books on it even classes you can take on it. Here in Michigan having legal medical marijuana. I know there are several classes and stuff at colleges specifically on indoor growing. The Medical Marijuana market is really weird here. You can not grow for your self. You have to have what is called a caregiver, who is a licensed grower of Marijuana. However a Caregiver I think can only be a caregiver to 5 people. So operations have to be small and limited. However this leads to a lot of caregivers.