How to Lower Nitrates in a Saltwater Aquarium

An excessive level of nitrates in a saltwater aquarium causes problems; the most obvious are algal blooms. Nitrates are some of the nutrients algae need and too many nutrients means an excess of algae, clogging equipment and reducing visibility in the water. More seriously, nitrates can be toxic to fish as some species cannot tolerate high levels. Many other species become lethargic and show faded colors when nitrate levels are high.

Things You'll Need

  • Nitrate test kit
  • Protein skimmer
  • Seaweed
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Instructions

    • 1

      Monitor nitrate levels with weekly tests and when they get too high (above about 10 to 20 parts per million), take steps to reduce them. It is safe to reduce levels to near zero.

    • 2

      Install a protein skimmer if you don't already have one. They remove organic waste and thus reduce nitrate levels. If you already have one, check to make sure it is working efficiently and consider upgrading it.

    • 3

      Perform extra partial water changes. Weekly or biweekly changes are part of general tank maintenance but if nitrate levels are high then you need to change a percentage of the water every couple of days. How much you change depends on your tank setup -- ranging from 10 percent to as much as a third of the water, says peteducation.com.

    • 4

      Stop overfeeding. Excess uneaten food just increases nutrient levels.

    • 5

      Introduce seaweeds. They absorb nitrates and keep levels under control.