There are a million different types of aquariums on the market, and with the number of choices available and the fact that there is no guaranteed formula for success for creating a saltwater aquarium it can be very difficult for individuals to choose which type of aquarium they should purchase. There are a number of factors which should be considered before the would be biologist ever sets foot inside a pet store.
The first is size. As trite as it may sound an aquarium is a definite example of a time when size matters. The size of the aquarium must be sufficient to hold the types and number of fish which the owner intends to place inside. Just as you would never attempt to place a large goldfish inside a small bowl neither should you attempt to place a large saltwater fish in a small aquarium. This is particularly true if you are attempting to add a small carnivore, such as one of the smaller breeds of shark, to your home. These predators need space to swim or they will slowly make themselves mad and perhaps even perish from the confinement (a bit melodramatic and Victorian, but true nonetheless).
There are several options for size when it comes to aquariums, and a good pet shop should be able to help advise consumers as to which size would best suit their needs.
Another consideration is materials. Glass and acrylic are the two choices most widely available on the market at the moment. Each has its own advantages and disadvantages. Glass is by far the more popular of the two due to the fact that it is less likely to scratch, allowing the sides to maintain their clarity. It is also considerably less expensive, an important consideration as it can cost a great deal of money to establish a saltwater aquarium and every advantage should be taken. Finally, the nature of the silicone sealant used in glass aquariums allows the tank to expand more readily when water is added.
Acrylic tanks come with their own advantages. There is almost no limit to the shape and size that an acrylic tank can take, allowing for a greater amount of creativity in tank design. It is also considerably more durable than glass, an important consideration if the aquarium is going to be displayed in a public place or if the owner has small children. Where a small bump may crack or otherwise damage a glass tank acrylic tanks are made of hardier stuff. It is also easier to adjust the filtration options on an acrylic tank, as it is not necessary to have the number of special tools available that are necessary to cut glass.
Whether acrylic or glass the would-be saltwater aquarium owner will probably have the option to purchase a pre-drilled tank to prevent overflow, giving the tank a much smoother appearance than the antiquated but still popular "hang on the back" method.
Buying an aquarium can be a tricky business; however, the truth of the matter is that as long as the ecosystem is properly designed and the tank cleaned thoroughly prior to use there is no right or wrong choice. It is all a matter of personal preference.