Despite the cooler outdoor temperatures, our aquariums can still become overheated and evaporate a large amount of water on daily basis. To make our homes comfortable, heaters and fires are used regularly, and these may lead to drastically fluctuating day-to-night temperatures. Additionally, the increased ambient temperature, coupled with aquarium heaters and lighting, the water temp could potentially climb higher in colder months than in warm months. For some, especially those with elaborate temperature regulating devices, aquarium temperatures aren’t an issue. But don’t let the cooler outside temps lull you into to a false sense of security when it comes to keeping your tank from overheating.