When Should I Dose Iron in My Planted Aquarium?

Like people, aquatic plants also require certain nutrients to thrive. Macronutrients, such as nitrogen, potassium, or phosphorous, are nutrients plants consume in large amounts. While micronutrients, like iron and boron, are nutrients plants only consume in small quantities. Many all-in-one liquid fertilizers like Easy Green already contain iron (Fe), so when is it necessary to dose additional iron in your planted tank?

Are my aquarium plants in need of more iron?

Iron is utilized by plants to produce chlorophyll, a green pigment that helps plants to absorb light and make energy. The plants that need bright lighting or are quick-growing will require a lot more energy. To get more energy, plants often need supplemental iron in order to produce more chlorophyll. An increase in iron can help your plants grow stronger and produce more vibrant colors.

Do my aquarium plants have an iron deficiency? An interesting fact about iron is that it cannot freely move from one area of the plant to another area that lacks it. Therefore, when your aquarium has low iron levels, the new leaves will appear pale or yellow due to insufficient chlorophyll. However, the bright colors of the older leaves will not fade.

Plants lacking iron might show yellowing or pallor on their newest leaves, with veins that are darker in color.

Are red plants dependent on iron? The primary function of iron is to create green pigments from chlorophyll, and not red pigment. However, red plants like scarlet temple or Ammannia gracilis can benefit from extra iron because many of them are also high light plants that consume more nutrients in general. Scientists are studying the function of red-leafed plant red pigments. These plants have higher levels of red chlorophyll than green chlorophyll. Under intense lighting, the red pigment may serve to protect leaves from excess light energy, and the amounts of green pigment may be decreased since not as much chlorophyll is needed to collect light photons. We recommend that aquarium hobbyists use a combination of high-light, carbon dioxide (CO2) injection and good nutrient doses (including iron) in order to increase the redness of their plants.

Certain red plants may cause the topmost leaves to turn pink, red, or purple. The lower leaves, however, remain green.

Bottom line: if your planted aquarium isn’t displaying nutrient deficiencies and you aren’t trying to grow high light plants, you probably don’t need to add any extra iron beyond what comes in Easy Green fertilizer. You also don’t require supplemental iron If you are using well water or iron-enriched substrate that already contains excess iron. Keep reading if your tank requires more iron than is being supplied.

How Often Should I Add Iron to My Aquarium?

Easy Iron is our iron supplement for enhanced plant growth that is completely safe for aquarium fish, shrimp, and snails. This iron supplement contains a concentrated mix of iron derived from iron DTPA and ferrous gluconate. Iron is used very quickly in aquariums. We recommend using 1 ml of Easy Iron for every 10 gallons of water, approximately 1-3 times per week. Each pump adds 0.26ppm of iron. A whole bottle can treat as many as 5,000 gallons.

If in doubt, begin with a low dosage for two weeks and gradually increase the dose over time. There have been reports of an increase in filamentous and hair algae due to excessive iron. Some articles about planted tanks recommend an aquarium water level between 0.1 to 0.5 ppm iron.

Why does Easy Green not contain more iron? Easy Green fertilizer is already a good choice for most planted aquariums. It contains trace amounts of iron. Easy Iron is a separate product that can also be added to other nutrients and minerals.

If you are having problems with your live aquatic plants and they do not appear to be caused by a lack of iron, check out our full article that describes other plant nutrient deficiencies to see if any of the symptoms match. Have fun with your tank and be sure to enjoy the outdoors every day.