There are several advantages and disadvantages of all-one-aquariums.
The pros include:
- Easy set-up: If you're a beginner, an all-in-one aquarium helps you avoid having to match filter capacity to tank size and all the other small technical hurdles that can plague a first aquarium. The entire kit has been designed to work together. Even expert aquarists can appreciate getting all the pieces in one package when setting up a new aquarium.
- Hand-holding for the beginner: Since all-in-one aquariums appeal to newbies, they usually include extra information on set-up, fish selection and care, and aquarium maintenance. Sure, you could buy a book on aquariums, but if you're buying a saltwater aquarium of a certain size, it's nice when the manufacturer recommends specific species and numbers of fish that would do well in that particular type of aquarium.
- Easier maintenance: Keeping an aquarium clean and healthy requires a regular maintenance schedule -- no matter what kind of aquarium it is. However, all-in-one aquariums are often designed with easy maintenance in mind. Filter cartridges are placed so they are easy to access and change or clean. The hood is designed to lift without interfering with the lights or filter. These things are possible without an all-in-one system, but often when you've bought all the parts separately, they don't work together quite as smoothly.
- Aesthetic appeal: Aquariums look wonderful, but an all-in-one tends to have a more unified design that can fit the décor of a room better than a glass tank with a basic hood might. All-in-ones can be designed to hide the mechanical and electronic components from view.
- Inadequate equipment: When you buy an all-in-one aquarium, you're trusting the manufacturer to have the appropriate heater, filtration and lighting for a given tank. They don't always get it right, though -- sometimes, inadequate filters are used to keep costs down. Insufficient lighting is another common problem, especially with reef systems.
- Difficulty of use: Retailers and manufacturers of all-in-one aquariums tout them as "plug and play" aquariums. This isn't really true -- you can't just add fish and water and have a successful aquarium. There's still a lot of work and expertise involved, don't think that using an all-in-one will be easier than it actually is.
- Hard to expand or adapt: If you're using basic glass tank for your aquarium, it's relatively simple to change your lighting set-up or add additional heaters. You can add more powerheads to generate currents and keep water flowing to stationary plants and anemones. Ironically, however, an all-in-one aquarium is somewhat restricted by its design. It was built for use with one particular filter or light, and using a different one or adding more might be impossible.
- Cost: Typically, an all-in-one aquarium costs more than a comparable aquarium built from separate parts. You pay a premium for having much of the work done for you.