How to Troubleshoot Freshwater Aquarium Plants With Brown Spots

Freshwater aquatic plants are prone to some diseases, parasites and nutrient deficiencies that can cause brown spots to appear. Aquariums can harbor bacteria and algae that can attack leaves and stems on aquatic plants. However, by checking a few important areas of your tank, you can both treat and prevent brown spots on your freshwater plants.

Things You'll Need

  • Nitrate testing kit
  • De-chlorinating fluid
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Instructions

    • 1

      Test the nitrate level of the water. Use a nitrate test kit available from pet stores or aquarium specialists. Excessive nitrate levels in freshwater is a common cause of brown spots, according to Monga Bay environmental science website. Change the water and add more oxygenating plants if your nitrate levels are high.

    • 2

      Look for signs that the brown spots are spreading into a light fuzz over the plant. This is a sign of diatoms, which thrives in low-light conditions. Increase light to the aquarium to get rid of the diatoms.

    • 3

      Check that the plant with brown spots isn't a freshwater Java fern. Brown spots on Java ferns are often harmless and indicate that the plant is growing and reproducing, according to Aquarium Garden.

    • 4

      Observe the behavior of fish. If they appear sluggish or swim erratically, there may be a problem with the aquarium water. The water could be poisoned, or very high in nitrates which could be affecting the freshwater plants.

    • 5

      Ensure that you're not using untreated tap water in your tank. Tap water should be treated with de-chlorinating fluid before being using in an aquarium. Chlorine can poison freshwater aquarium plants, causing brown patches.