Seachem Flourish Iron 500 mL – Planted Aquarium Iron Supplement
Seachem Flourish Iron 500 mL is a highly concentrated ferrous iron supplement formulated for freshwater planted aquariums. It contains 10,000 mg/L of iron derived from ferrous gluconate, providing iron in the soluble Fe²⁺ form that aquatic plants can readily use.
Iron is essential for chlorophyll production and healthy new plant growth. Flourish Iron can help prevent or correct iron-deficiency symptoms such as pale young leaves, yellowing between leaf veins, short slender stems, and reduced coloration in red, orange, or bronze aquarium plants.
Key Features
- Highly Concentrated Iron: Contains 10,000 mg/L of iron for targeted planted-aquarium supplementation
- Ferrous Gluconate: Supplies soluble ferrous iron in the Fe²⁺ form preferred by aquatic plants
- Supports Chlorophyll Production: Helps maintain healthy green tissue and active new growth
- Corrects Iron Deficiency: Useful when young leaves appear pale or yellow between the veins
- Supports Plant Coloration: Helps maintain iron availability for red, orange, pink, and bronze aquarium plants
- Targeted Supplement: Allows iron to be adjusted independently from other plant nutrients
- Large 500 mL Bottle: Convenient for larger planted aquariums, multiple tanks, and regular dosing
Product Information
- Brand: Seachem
- Product: Flourish Iron
- Size: 500 mL
- Equivalent Size: Approximately 17 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
- Recommended Iron Level: Approximately 0.10 mg/L
Best Used For
- Freshwater planted aquariums
- Red, orange, pink, and bronze aquarium plants
- Alternanthera species
- Ludwigia species
- Rotala species
- Fast-growing stem plants
- Aquariums showing signs of iron deficiency
- Pale or yellow young leaves
- Targeted iron supplementation alongside complete fertilizers
- Low-tech and high-tech planted aquariums
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. Use a dosing syringe when smaller or more precise amounts are required.
The standard dose raises aquarium iron by approximately 0.25 mg/L. Plants use iron rapidly, so the measurable concentration may fall soon 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, visible deficiency symptoms, water testing, and aquarium conditions.
Testing Iron Levels
Seachem recommends maintaining approximately 0.10 mg/L of iron. Because plants may absorb Flourish Iron rapidly, test the aquarium within 30 minutes of dosing when evaluating the iron concentration.
A low or unreadable result later in the day does not necessarily mean the product failed. The iron may already have been absorbed by plants or removed from the water column.
Do not repeatedly add more product solely because a later test shows little measurable iron. Consider plant appearance, growth, dosing history, and the accuracy of the test kit.
Signs of Iron Deficiency
- Pale or yellow young leaves
- Yellow tissue between green leaf veins
- New leaves appearing lighter than older leaves
- Short or slender stems
- Weak new growth
- Reduced red, orange, pink, or bronze coloration
Iron is relatively immobile within plants, so deficiency symptoms usually appear first on young leaves and new growth rather than older leaves.
Supporting Red Aquarium Plants
Adequate iron availability can help support healthy coloration in plants such as Alternanthera, Ludwigia, Rotala, and other red or bronze species. However, iron alone does not determine whether a plant develops intense red coloration.
Plant genetics, lighting intensity, carbon availability, nitrate levels, overall nutrient balance, and aquarium stability also influence color. Adding excessive iron will not compensate for inadequate lighting, carbon, or other missing nutrients.
Using Flourish Iron with Flourish
Seachem Flourish contains a smaller amount of iron along with a broader mixture 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 be dosed more regularly because iron is rapidly depleted, while Flourish is normally used less frequently. Keeping the products separate allows iron to be adjusted without repeatedly adding every nutrient found in Flourish. :contentReference[oaicite:1]{index=1}
Using Flourish Iron with CO₂
Flourish Iron does not require injected carbon dioxide to supply iron to aquarium plants. It may be used in both low-tech and high-tech planted aquariums.
Pressurized CO₂ can increase plant growth and nutrient demand. Aquariums with strong lighting and injected CO₂ may therefore consume iron more rapidly than low-light aquariums.
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 nitrogen, phosphorus, potassium, and trace nutrients balanced
- Do not increase iron solely to compensate for poor lighting or unstable CO₂
- Continue regular water changes and aquarium maintenance
- Keep a dosing log to track plant response
Important Planted Aquarium Note
Flourish Iron is a targeted iron supplement and does not replace a complete planted-aquarium fertilizer. Aquarium plants may also require nitrogen, phosphorus, potassium, magnesium, trace elements, carbon, suitable lighting, and stable water conditions.
Yellowing leaves can have several causes, including nitrogen deficiency, magnesium deficiency, root damage, poor lighting, unstable carbon dioxide, or general plant stress. Iron deficiency is more commonly associated with chlorosis that begins on young leaves.
Adding excessive iron does not guarantee stronger growth or coloration. Dose according to plant demand, visible symptoms, and testing rather than automatically following a fixed schedule.
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 measured iron levels. Some heavily planted aquariums may require regular or daily dosing, while slower-growing systems may require less.
What form of iron does Flourish Iron contain?
It contains ferrous gluconate, which supplies soluble iron in the Fe²⁺ form.
How concentrated is Flourish Iron?
It contains 10,000 mg/L of iron, equivalent to 1% iron.
What are common signs of iron deficiency?
Common signs include pale or yellow young leaves, green veins surrounded by yellow tissue, short slender stems, and weak new growth.
Does Flourish Iron make red plants more colorful?
Adequate iron can support healthy coloration, but plant color also depends on genetics, lighting, carbon availability, nitrate levels, and overall nutrition.
Is Flourish Iron needed when using Flourish?
Flourish contains some iron, but heavily planted aquariums or systems with high iron demand may benefit from additional Flourish Iron.
When should I test iron after dosing?
Seachem recommends testing within 30 minutes because aquarium plants can use the iron rapidly.
Do I need injected CO₂ to use Flourish Iron?
No. Flourish Iron may be used with or without injected CO₂. High-growth CO₂ systems may consume iron more quickly.
Can Flourish Iron be used in low-light aquariums?
Yes, when plants show a need for additional iron. Low-light aquariums usually grow more slowly and may require less frequent dosing.
Can excessive iron cause aquarium problems?
Excessive or unbalanced fertilization may contribute to nutrient imbalance or algae issues. Measure carefully and avoid unnecessary overdosing.
Available at Tropical Treasures Wyo
Seachem Flourish Iron 500 mL provides concentrated ferrous iron for preventing 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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