How is a canopy set-up? I have never really seen how it works. I am thinking about buyiny a new system off od craigslist and the guy says that the canopy just sits on top of the tank. His lights aren't mounted to the canopy, they sit under it. he has a freshwter system. I have a saltwater. I have salwater lighting on my tank that is not in a canopy. Can I put this canopy over my lighting. I am worried about air flow for the fans. Thanks
Sometimes canopies are open in the back to allow the airflow. They are designed to have light hoods under them but make sure your lighting system clears. I have heard of people having to do some work by carving out places for the mounts. Also, make sure the fan for your light system is not facing up (considering heat rises, this might make it really hot inside the canopy).
You may have to modify the canopy to fit your needs. As uscamaro said, most canopies are open in the back for airflow. Some people add fans to facilitate airflow. I've seen MH lights in canopies, so covering your lights shouldn't be a problem.