1. It is not advisable to leave your aquarium lights on at all times for the aquarium. You should keep the lights on for 8-12 hour periods at a time. If you want to keep the tank lights on when you arrive home, simply get a timer for the lights so your fish stay on a schedule.
2. Avoid placing your aquarium near a radiator or any other form of heater. The heat given off by these devices can easily upset the temperature balance in your aquarium. Raised temperature levels can kill off the fish and plants that you have in your aquarium.
3. It is generally recommended to use natural gravel for the aquarium. Colored gravel can be used, as long as it is professionally made, certain cheaply made color gravels can be toxic to fish in your aquarium.