How to Get Nitrite Levels Back to 0 in a Saltwater Aquarium

Nitrites are a toxic byproduct of the bacterial breakdown of ammonia excreted by fish and other aquarium dwellers. Although according to Daniel E. Terlizzi, Water Quality Specialist at the University of Maryland, saltwater fish are less susceptible to nitrite toxicity than their freshwater cousins, nitrite levels in a healthy saltwater aquarium should ideally be undetectable. Nitrite levels above 0.25 ppm (0.25 milligrams per milliliter) require a prompt partial water change.

Things You'll Need

  • 5-gallon buckets (2)
  • Marine aquarium salt mix
  • Siphon hose
  • Nitrite test kit
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Instructions

    • 1

      Prepare a bucket of replacement seawater with the correct marine salt mix for your aquarium. Preheat the water to the appropriate temperature, if necessary.

    • 2

      Unplug the aquarium̵7;s light, heater and filtration system. Remove the light fixture. Place an empty bucket near enough to the aquarium that the hose will easily reach from one to the other. The bucket must also be lower than the aquarium.

    • 3

      Wash your hands and the siphon hose. Fill the hose with water from the sink. Make sure it contains no air bubbles. Cover each end of the hose with your thumbs.

    • 4

      Put one end of the hose in the aquarium while keeping your thumbs over both ends. Put the other end of the hose over the empty bucket. Remove your thumbs from both ends of the hose. The water in the aquarium will begin flowing toward the bucket. Remove about 25 percent of the water in the aquarium. To stop siphoning, crimp the hose above the bucket.

    • 5

      Refill your aquarium with the replacement seawater you prepared in Step 1. Pour the water slowly and carefully to avoid buffeting and distressing your fish.

    • 6

      Conduct a nitrite test according to the manufacturer̵7;s instructions. If testing shows that the nitrite levels are still elevated, continue changing the water in 25-percent increments ̵1; and conducting nitrite tests ̵1; until nitrite levels are below 0.25 ppm.

    • 7

      Replace the light fixture. Plug the light, heater and filtration system back in.

    • 8

      Test the water daily and perform additional 25-percent water changes as necessary. According to zoologist and aquarium expert John H. Tullock, don̵7;t feed your fish until the nitrite levels have stabilized at zero.