1. It is not recommended to keep your aquarium where it receives direct sunlight. Exposure to direct sunlight can upset the balance of the aquarium and can raise aquarium temperature levels. It is best to keep your aquarium in a place where you can control the lighting.
2. If you have a protein skimmer you should shut it off when you are adding medicine to your aquarium. The protein skimmer will remove any medicines added to the aquarium.
3. It is generally a good practice to purchase the largest aquarium that you can actually afford. A larger aquarium will be less susceptible to quick changes in the chemistry, and will offer much more stability.