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One of the first questions people ask when considering starting a saltwater or marine aquarium is, “what size tank should I get?”
When visiting your local pet store and looking at aquariums, the selection and variety can often be overwhelming. Not to mention that when you ask this question to different sales people you will frequently get a different answer on which tank size is recommended for saltwater.
The bigger the better
The best answer that nobody will dispute is: the bigger, the better.
The concept here is that the more water you have the more buffer you have for problems. In smaller tanks, when things go bad, they go bad rather quickly due to the smaller amounts of water.
Other benefits offered by larger saltwater fish tanks are more surface area for gas exchange, more area for the fish to swim and thrive, and more room for expansion so that a tank upgrade doesnt occur too soon. A member of the 3Reef.com put it best when they said:
One drop of acid in the ocean is undetected, one drop of acid in a cup of water is off the scale. Aquariums are the same way.
Minimum size for a saltwater aquarium
Since many of you like me don’t have unlimited funds and space, nor do you have your own personal city aquarium, you are most likely wondering what the minimum recommended size is.
Most experienced aquarists, including myself would recommend going with at least a 55 gallon and preferably a 75 gallon.
The 75 gallon is actually similar in size, but is more expensive and harder to find.
55 gallon saltwater tanks are relatively cheap due to their popularity in the freshwater aquarium hobby. If you have the space and the money, get the 75 gallon over the 55.
The 75 gallon tank provides the same length and height, but a deeper depth (by about 6 inches). This provides more room for live rock, for your fish to swim, for surface area.
The honest answer
The honest answer is go with the size you can afford, house, and maintain – recognizing the bigger the better. The smaller your tank, the more maintenance it will require.
I have read and personally seen people with 5 and 10 gallon saltwater tanks that are far more successful than my current 75 gallon.
In a small aquarium you just have to be militant about frequent water changes, checking the tank parameters and maintaining good water flow. I’m militant, but not militant enough yet.
A frequent choice by many new hobbyists is the 30 gallon. Its common due to its availability (like the 55) and due to many freshwater aquariums being 30 gallons in size. Again a 30 gallon will do well, but you will need to frequently maintain it.