Aquarium Tank Size | Length, Width And Height

After you have chosen a suitable location in your home for your new saltwater aquarium, the next thing to decide on is the aquarium tank size and the actual aquarium dimensions for your living space.

Aquarium Tank Size | The Bigger The Water Volume, The Better

Try to go with the largest aquarium tank size your budget and space will allow.

The larger the tank size, the greater the water volume and the more stable the water parameters will be.  And the more stable the water parameters, the better the water quality will be.  Stable parameters and good water quality are what our delicate marine aquarium inhabitants require.

Aquarium Tank Size Considerations | Length, Width and Height

Tank Length

Not surprisingly, when considering aquarium tank size, length is the first thing we actually think about.  Although there is only a 5 gallon difference in water volume between a tank that is 48″ x 24″ x 24″ and a tank that is 72″ x 20″ x 20″, the longer 6 foot (72″) tank would look far more impressive.  A long tank really let’s us run wild with all kinds of live rock aquascaping ideas.  Provided that a 6 foot long space to put your tank is available of course!

Aquarium Size | Length Width Height

Length, width and height | aquascaping possibilities

And if you haven’t worked it out already the 4 foot aquarium mentioned above would hold a total water volume of 120 gallons while the 6 foot tank will hold 125 gallons!

Also, the longer the tank, the greater the surface area of the water, and the better the gas exchange of carbon dioxide and oxygen at the surface of the water.

Adequate tank length of 6 feet or more is also important if you’re planning to keep a small school of fast swimming fish like tangs

Tank Width

The width of a tank refers to the distance from the front glass to the back of the aquarium.

A wider aquarium will allow for better gas exchange at the water surface, increasing dissolved oxygen.

Aesthetically, a wider tank width will allow for more aquascaping possibilities.  Bear in mind that underwater, everything will appear closer than it actually is.  A narrow aquarium will only emphasize this optical illusion even more.

Tank Height

Tank height is another important consideration when deciding on aquarium tank size.

A tall tank allows for breathtaking liverock aquascaping.  Anything more than 2 feet in height would be considered a tall tank

However, the taller the tank the more difficult it will be to perform tank maintenance at the lower portion of the tank.  Vacuuming the sandbed, pruning algae, or attaching corals to rock in the lower half of a tall tank become nearly impossible without getting one’s arms and body wet!

And unless you’re using metal halide lights over your aquarium, fluourescent aquarium lighting will also not be able to penetrate very deep tanks efficiently.

Tall But Narrow Tanks Should Be Avoided

The taller a tank, the wider it will need to be also, to allow for efficient gas exchange and oxygenation.  As far as aquarium tank size, extremely tall but narrow tanks are usually poorly oxygenated because of the lower surface area compared to the total volume of water.

Calculating Water Volume in US Gallons

To calculate the water volume of your aquarium in US gallons, multiply the length, width and height in inches and divide the sum by 231.

An aquarium that is 48″ x 18″ x 25″ for example would hold a total volume 90 US gallons.

(48 x 18 x 25) divided by 231 = 90


Links to more Saltwater Aquarium Setup pages:

The Ideal Location For Your Saltwater Aquarium

Ready-Made Aquariums

Acrylic Aquariums

Custom-Built Glass Aquariums

Drilled Overflows Vs. Siphon Overflows

Aquarium Stands

Why Beginning Hobbyists Should Avoid Starting A Nano Aquarium

Aquarium Chillers

Aquarium Sump



Aquarium Covers | Put A Lid On It!

Cooling Fans


What You Don’t Need For Your Saltwater Aquarium!



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