Of course, depending on what size you choose, you'll need to consider the right space to put it. Space must not just accommodate the volume of your aquarium, but also the weight of the tank once filled. Remember, a gallon of water weighs 8 lbs. and you need to be sure your set-up is structurally sound. Other things to consider about the space: can you get it wet? Is there a nearby water source? Access to electrical outlets? Is sunlight a factor? How about ambient temperature?

You likely want to keep some fish, but do you also want to keep live rock or set up a reef aquarium. Both the live rock and reef options provide a measure of natural filtration, creating a healthier environment for your fish, one that is often seen as preferable to attempting to keep a tank in balance with mechanical and chemical filters alone.

Whichever option you do end up choosing, you'll need a filtration system, and in terms of keeping a healthy  saltwater tank, a good filtration system is equally important to the actual aquarium.