The Importance of Water Testing in Saltwater Aquariums: A Beginner's Guide

Whether you're in the planning stage or have already set up your first marine aquarium, add water testing to your to-do list. Regularly testing the contents of the water in your saltwater aquarium lets you know if the water is balanced, or ideal, for your oceanic friends to thrive. 

How often should you test your aquarium water?

Poor water quality causes most environmentally induced fish diseases. Testing your aquarium water often allows you to stay ahead of potential water quality issues and fish health concerns. 

Make it a habit to test your water after each partial water change. This happens approximately once a week in new set-ups and once or twice a month in established saltwater aquariums. Also, smaller tanks tend to be less stable since temperature, salinity, pH, and other water parameters can fluctuate more rapidly than in larger tanks, making them require more frequent water testing.

Remember, as an aquarist, you can test your aquarium water as often as you'd like. Some do a water test a few days after adding new fish, plants, or corals to see if the water quality has shifted.

It's smart to keep a log of your water test results so you can notice any trends when you add fish, do a partial water change, or add a chemical water adjuster. Soon you'll understand how your tank ebbs and flows when you make changes.

What tests should you do on your saltwater aquarium?

You want to test several water content levels in your saltwater aquarium. The first is salinity, or salt density, in the water.

Use a Coralife Deep Six Hydrometer to read your aquarium's salt levels. This tool uses a specific gravity meter to let you know the PPT (parts per thousand) of salt in the water as well as the specific gravity. The ideal reading will vary depending on what you keep in your marine water world. Reef systems thrive at 1.024 to 1.026 specific gravity, while fish-only aquariums stay healthy at 1.021 to 1.023 specific gravity.

If the salinity is low, add aquarium salt. For example, Coralife BioCube Marine Salt gets mixed at a ratio of one level scoop of product per gallon of water to achieve 1.026 specific gravity (or approximately 35 PPT). If the salinity reading is too high, do a partial water change and add less salt to the new water being added.

Note: It can take up to three hours for marine salt to fully dissolve into water. Wait to do a follow-up water test after this time.

To test other water content levels, use Aqueon 7-in-1 Aquarium Test Strips. These disposable strips provide quick results (approximately 30 seconds) after dipping in your marine aquarium water.

You'll learn information about your aquarium's levels of:

• Free Chlorine

• Hardness

• Nitrate

• Nitrite

• Iron levels

• pH

• Total Alkalinity

Finally, use Aqueon Ammonia Aquarium Test Strips to determine the levels of ammonia in your saltwater aquarium. Simply dip a strip into the aquarium water and wait two minutes before reading the results.

How do you interpret water test strip results?

To interpret your saltwater aquarium water testing results, compare the wet test strips to the color-coded results charts on the Aqueon 7-in-1 Aquarium Test Strips and Ammonia Aquarium Test Strips packages. This will help you identify any issues, or imbalances, in the water.

Then, you can take corrective action to balance the water. You might discover you need to add a chemical water adjuster to elevate or decrease a specific reading slightly, do a water change to remove high levels of pollutants (such as ammonia or nitrites), or change the filter media/filter cartridge to boost the aquarium's filtration and cleaning of the water. 

For example, if you get a low alkalinity (KH) reading, you want to add Coralife Nano Reef Part A/B. This chemical water adjuster also helps to stabilize pH levels. So use it if you notice either of these readings varying often.

If you discover a slight elevation in ammonia or nitrites when testing your aquarium water, try adding a Coralife Pure live beneficial marine bacteria and enzyme ball (one per 30 gallons of water) per week to keep water maintenance easy. This water adjuster helps break down organic waste and make the water more clear.

Understanding Saltwater Aquarium Water Testing

After you've tested your aquarium a few times, you'll get the hang of the various tests, reading the results, and making adjustments to your aquatic environment to ensure your fish friends stay healthy.

Learn more about maintaining your saltwater aquarium in "Common Issues with Saltwater Aquariums and How to Fix Them."