Seachem Flourish Iron 250 mL – Planted Aquarium Iron Supplement

Seachem Flourish Iron 250 mL is a highly concentrated ferrous iron supplement formulated for freshwater planted aquariums. It provides iron in the ferrous, or Fe²⁺, form that remains soluble in aquarium water and is readily available for plant uptake.

Iron is essential for chlorophyll production and healthy new growth. Flourish Iron can help correct iron deficiency symptoms such as pale or yellowing young leaves, short slender stems, and reduced coloration in red, orange, and pink aquarium plants.

Key Features

• Concentrated Iron Supplement: Contains 10,000 mg/L of iron for targeted planted-aquarium dosing
• Ferrous Gluconate Iron: Supplies iron in the soluble Fe²⁺ form preferred by aquatic plants
• Supports Chlorophyll Production: Helps plants maintain healthy green tissue and active new growth
• Corrects Iron Deficiency: Useful when new leaves show chlorosis or pale coloration
• Supports Red Plant Coloration: Helps maintain the iron availability needed by red and fast-growing aquarium plants
• No Added Nitrogen or Phosphate: Allows targeted iron supplementation without intentionally adding macronutrients
• Convenient 250 mL Bottle: Suitable for small, medium, and regularly fertilized planted aquariums

Product Information

• Brand: Seachem
• Product: Flourish Iron
• Size: 250 mL
• Equivalent Size: Approximately 8.5 fl oz
• Product Type: Freshwater aquarium plant iron supplement
• Iron Source: Ferrous gluconate
• Iron Concentration: 10,000 mg/L
• Guaranteed Iron: 1%
• Aquarium Type: Freshwater planted aquariums
• Target Iron Level: Approximately 0.10 mg/L

Best Used For

• Freshwater planted aquariums
• Red, orange, and pink aquarium plants
• Fast-growing stem plants
• Aquariums showing signs of iron deficiency
• New leaves with pale or yellow tissue
• Short, slender, or weak new stems
• Low-tech and high-tech planted aquariums
• Targeted iron supplementation alongside complete plant fertilizers

How to Use

Use one capful, or 5 mL, of Seachem Flourish Iron for every 50 US gallons of aquarium water or as needed to maintain an iron concentration of approximately 0.10 mg/L.

Each thread inside the cap represents approximately 1 mL for smaller aquariums. Use a dosing syringe when precise amounts below 1 mL are required.

The standard 5 mL dose per 50 gallons raises iron by approximately 0.25 mg/L. Iron is used quickly by aquarium plants, so the concentration may fall rapidly after dosing.

Approximate Dosage Guide

• 5-Gallon Aquarium: Approximately 0.5 mL
• 10-Gallon Aquarium: Approximately 1 mL
• 20-Gallon Aquarium: Approximately 2 mL
• 40-Gallon Aquarium: Approximately 4 mL
• 50-Gallon Aquarium: 5 mL
• 75-Gallon Aquarium: Approximately 7.5 mL
• 100-Gallon Aquarium: 10 mL

These amounts are proportional calculations based on Seachem’s standard dosage. Actual dosing frequency should be adjusted according to plant demand, aquarium conditions, iron testing, and visible deficiency symptoms.

Testing Iron Levels

Seachem recommends maintaining an iron concentration of approximately 0.10 mg/L. Because plants can use Flourish Iron rapidly, test the water within 30 minutes of dosing when checking the aquarium’s response.

A low or unreadable iron result several hours after dosing does not necessarily mean the supplement failed. The iron may already have been absorbed by plants or otherwise removed from the water column.

Do not continuously add more product solely because a later test shows no measurable iron. Consider plant growth, deficiency symptoms, dosing history, and the reliability of the test kit.

Signs of Iron Deficiency

• Yellowing or pale coloration on new leaves
• Green veins surrounded by yellow tissue
• New leaves emerging lighter than older leaves
• Short or slender stems
• Reduced red, orange, or pink coloration
• Slow or weak new growth

Iron is relatively immobile within plants, meaning plants cannot easily move stored iron from older leaves into new growth. For this reason, deficiency symptoms generally appear first on young leaves.

Using Flourish Iron with Flourish

Seachem Flourish contains a smaller amount of iron along with a broad blend of plant nutrients and trace elements. Flourish Iron provides a separate, concentrated iron source for aquariums where plant demand exceeds the iron supplied by a complete fertilizer.

Seachem notes that Flourish Iron may require more frequent dosing because iron is rapidly depleted, while Flourish is normally dosed less often. Keeping these products separate allows iron to be adjusted without repeatedly adding every nutrient contained in Flourish. :contentReference[oaicite:1]{index=1}

Using Flourish Iron with Other Fertilizers

Flourish Iron may be used alongside carbon supplements, complete plant fertilizers, root tabs, potassium supplements, and other planted-aquarium products when each is dosed according to its label.

Avoid directly mixing concentrated fertilizers together in the same container unless the manufacturer specifically permits it. Add products separately to an area with good aquarium water movement.

Planted Aquarium Tips

• Measure each dose carefully
• Test iron within 30 minutes when monitoring concentration
• Observe new leaves for signs of deficiency
• Use a complete fertilizer for nutrients beyond iron
• Maintain suitable lighting and carbon availability
• Keep nitrate, phosphate, potassium, and trace nutrients balanced
• Do not increase iron solely to compensate for inadequate lighting or carbon
• Continue regular water changes and aquarium maintenance
• Keep a log of dosing amounts and plant response

Important Planted Aquarium Note

Flourish Iron is a targeted iron supplement and does not replace a complete planted-aquarium fertilizer. Plants may also require nitrogen, phosphorus, potassium, magnesium, trace elements, carbon, suitable lighting, and stable water conditions.

Yellowing leaves may have several causes, including nitrogen deficiency, magnesium deficiency, root damage, poor lighting, unstable carbon dioxide, or general plant stress. New-growth chlorosis is more strongly associated with iron deficiency than yellowing that begins on older leaves.

Adding excessive iron does not guarantee stronger plant coloration and may contribute to nutrient imbalance. Dose according to plant demand and testing rather than automatically increasing the amount.

Frequently Asked Questions

What is Seachem Flourish Iron used for?
Flourish Iron supplies concentrated ferrous iron for freshwater aquarium plants and helps prevent or correct iron deficiency.

How much Flourish Iron should I use?
Use 5 mL for every 50 US gallons or as needed to maintain approximately 0.10 mg/L iron.

How often should Flourish Iron be dosed?
Dose according to plant demand and iron levels. Because iron is used rapidly, some heavily planted aquariums may require frequent or daily supplementation.

What form of iron does Flourish Iron contain?
It contains ferrous gluconate, which supplies soluble ferrous iron in the Fe²⁺ form.

Does Flourish Iron add nitrogen or phosphate?
No nitrogen or phosphate is listed in the guaranteed analysis. It is intended as a targeted iron supplement.

What are common signs of iron deficiency?
Common signs include yellowing between the veins of new leaves, pale new growth, short slender stems, and reduced coloration.

Does Flourish Iron make red plants redder?
Adequate iron can support healthy coloration, but red plant color also depends on genetics, lighting, carbon availability, nitrate levels, and overall nutrient balance.

Is Flourish Iron needed when using Flourish?
Flourish contains iron, but densely planted aquariums or tanks with high iron demand may benefit from additional Flourish Iron.

When should I test iron after dosing?
Seachem recommends testing within 30 minutes because the iron may be used rapidly by aquarium plants.

Why does my test show no iron shortly after dosing?
Plants may have absorbed the iron quickly, or the test kit may not detect all forms equally. Evaluate dosing history and plant response before adding more.

Can Flourish Iron be used in a low-light aquarium?
Yes, when plants show a confirmed need for additional iron. Low-light aquariums usually have slower nutrient demand, so conservative dosing is appropriate.

Can too much iron cause algae?
Excessive or unbalanced fertilization can contribute to aquarium problems. Use the recommended dosage and maintain balanced lighting, carbon, and nutrients.

Available at Tropical Treasures Wyo

Seachem Flourish Iron 250 mL provides concentrated ferrous iron for correcting iron deficiency and supporting healthy freshwater aquarium plant growth. Visit Tropical Treasures Wyo in Cheyenne, Wyoming, to shop Seachem plant supplements, live aquarium plants, root tabs, planted substrates, aquarium lighting, water test kits, and aquascaping essentials.

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