The pH in a Saltwater Aquarium

The pH is a concern in every type of aquarium, although generally more flexible and allowing for a broader range in freshwater fish. Saltwater aquariums that have only fish, can also tolerate a range of levels, however when it is a reef aquarium, the balance becomes a little more delicate, and more important to survival and enabling a colony to thrive.

Put simply, pH stands for the "power of hydrogen", and while the scientific explanation involving ions and chemicals can be very complex, what it come down to, is the measure of acidity or alkaline content in your aquarium water.

The average or neutral level is a reading of 7. Above that is alkaline, which is desirable for saltwater aquariums, and below it is acidic water, which would not be suitable.

Most saltwater tanks will have a pH of anywhere from 7.4-8.6, but a reef tank will require a higher level than that.

Acids getting into the tank, will lower your pH level. The most common origin of acidic content is a build-up of carbon dioxide breathed out by fish when the environment has insufficient means for gas exchanges; organic acids that come from metabolic wastes such as excrement, dead fish and leftover food; and nitric acid that is the product of biological means of filtration.

In the sea, there would be natural chemicals to "buffer" or balance out these acids, but they do not exist in a man-made environment. That's why regular monitoring of your tank's pH level is important, so that you can add a buffer solution if necessary. But the best way of maintaining a good pH balance, is still the regular replacement of 20% of your aquarium's water content, which will replace natural buffers and trace minerals.

Recommended: You'll find more information on starting your own saltwater aquarium, we recommend picking up the Complete Encyclopedia of the Saltwater Aquarium.

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