Seachem Flourish Potassium 250 mL – Planted Aquarium Potassium Supplement

Seachem Flourish Potassium 250 mL is a concentrated potassium supplement formulated for freshwater planted aquariums. Potassium is an essential macronutrient involved in plant growth, photosynthesis, nutrient transport, and the development of healthy leaves, stems, and roots.

Flourish Potassium contains 50,000 mg/L of elemental potassium derived from potassium sulfate. It allows aquarium keepers to increase potassium without intentionally adding nitrogen or phosphate, making it useful for targeted nutrient control in low-tech and high-tech planted aquariums.

Key Features

• Concentrated Potassium Supplement: Contains 50,000 mg/L of elemental potassium
• Supports Healthy Plant Growth: Supplies potassium needed for leaves, stems, roots, and normal plant development
• Helps Prevent Deficiency: Useful when older leaves show yellowing, browning, pinholes, or weak growth
• No Added Nitrogen or Phosphate: Allows potassium to be adjusted independently from other macronutrients
• Potassium Sulfate Source: Provides potassium without relying on potassium nitrate or potassium phosphate
• Low-Tech & High-Tech Use: Suitable for a wide range of freshwater planted aquarium setups
• Convenient 250 mL Bottle: Ideal for small to medium planted aquariums and targeted dosing

Product Information

• Brand: Seachem
• Product: Flourish Potassium
• Size: 250 mL
• Equivalent Size: Approximately 8.5 fl oz
• Product Type: Freshwater aquarium plant potassium supplement
• Potassium Source: Potassium sulfate
• Elemental Potassium Concentration: 50,000 mg/L
• Guaranteed Soluble Potash: 6%
• Aquarium Type: Freshwater planted aquariums
• Standard Dosage: 5 mL per 30 gallons

Best Used For

• Freshwater planted aquariums
• Rapidly growing planted tanks
• Low-mineral source water
• RO or softened water used in planted aquariums
• Older leaves showing potassium-deficiency symptoms
• Plants developing pinholes or browning leaf tissue
• Weak stems or roots
• Low-tech and high-tech planted aquariums
• Targeted potassium dosing alongside complete fertilizers

How to Use

Use one capful, or 5 mL, of Seachem Flourish Potassium for every 30 US gallons of aquarium water. Repeat two to three times per week or as needed in response to plant growth and signs of potassium deficiency.

Each standard dose raises potassium by approximately 2 mg/L. Calculate dosage using the aquarium’s estimated actual water volume after accounting for substrate, rocks, driftwood, decorations, and equipment.

Use a dosing syringe for small aquariums or when amounts below one capful are required. Add the supplement to an area with good aquarium water movement.

Approximate Dosage Guide

• 5-Gallon Aquarium: Approximately 0.8 mL per dose
• 10-Gallon Aquarium: Approximately 1.7 mL per dose
• 20-Gallon Aquarium: Approximately 3.3 mL per dose
• 30-Gallon Aquarium: 5 mL per dose
• 40-Gallon Aquarium: Approximately 6.7 mL per dose
• 55-Gallon Aquarium: Approximately 9.2 mL per dose
• 75-Gallon Aquarium: Approximately 12.5 mL per dose
• 100-Gallon Aquarium: Approximately 16.7 mL per dose

These amounts are proportional calculations based on Seachem’s standard dosage. Dose two to three times per week or adjust according to plant demand and visible deficiency symptoms.

Signs of Potassium Deficiency

• Yellowing on older leaves
• Browning or dead areas on older leaves
• Pinholes developing in leaf tissue
• Weak stems
• Weak or underdeveloped roots
• Declining older leaves while new growth remains less affected
• Reduced overall plant growth

Potassium is mobile within plants, meaning plants can move it from older tissue into new growth. For this reason, potassium-deficiency symptoms often appear on older leaves first.

Why Potassium Matters

Potassium is one of the primary macronutrients required by aquarium plants. It supports many biological functions, including nutrient transport, enzyme activity, water regulation, photosynthesis, and the development of healthy plant tissue.

Potassium may become depleted in rapidly growing planted aquariums or when the source water contains low mineral levels. When potassium becomes the limiting nutrient, plant growth may slow even when lighting, carbon, nitrogen, and phosphorus are otherwise available.

No Added Nitrogen or Phosphate

Many common potassium sources also contain nitrate or phosphate. This can make it difficult to increase potassium without simultaneously changing the aquarium’s nitrogen or phosphorus levels.

Flourish Potassium is derived from potassium sulfate. This allows potassium to be supplemented independently, making it useful when nitrate and phosphate are already within the desired range.

Using Flourish Potassium with Flourish

Seachem Flourish contains a broad blend of trace and minor nutrients but is not intended to provide large amounts of the primary macronutrients nitrogen, phosphorus, or potassium.

Flourish Potassium may be used alongside Flourish when aquarium plants require additional potassium. It may also be combined with Seachem Flourish Nitrogen and Flourish Phosphorus as part of a targeted macronutrient routine.

Using Flourish Potassium with Other Fertilizers

Flourish Potassium may be used alongside complete plant fertilizers, root tabs, iron supplements, carbon 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 each product separately into an area with good water circulation.

Planted Aquarium Tips

• Measure each dose carefully
• Observe older leaves for deficiency symptoms
• Use a dosing syringe for small aquariums
• Maintain balanced nitrogen, phosphorus, potassium, and trace nutrients
• Provide suitable aquarium lighting
• Maintain stable carbon availability
• Remove severely damaged or decaying leaves
• Continue regular water changes and aquarium maintenance
• Keep a dosing log to track plant response

Important Planted Aquarium Note

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

Yellowing and damaged leaves can have several causes, including nitrogen deficiency, magnesium deficiency, iron deficiency, inadequate carbon, poor lighting, root damage, or unstable aquarium conditions. Potassium deficiency is more commonly associated with symptoms appearing first on older leaves.

Adding excessive potassium does not guarantee faster plant growth. Dose according to plant demand and aquarium conditions rather than automatically increasing the amount.

Frequently Asked Questions

What is Seachem Flourish Potassium used for?
Flourish Potassium supplies concentrated potassium for freshwater aquarium plants and helps prevent or correct potassium deficiency.

How much Flourish Potassium should I use?
Use 5 mL for every 30 US gallons two to three times per week or as needed.

How much does the standard dose raise potassium?
A dose of 5 mL per 30 gallons raises potassium by approximately 2 mg/L.

How concentrated is Flourish Potassium?
It contains 50,000 mg/L of elemental potassium.

What is the potassium source?
The potassium is derived from potassium sulfate.

Does Flourish Potassium add nitrogen or phosphate?
No. It is formulated to increase potassium without intentionally adding nitrogen or phosphate.

What are common signs of potassium deficiency?
Signs may include yellowing, browning, pinholes, or dead tissue on older leaves, along with weak stems and roots.

Does Flourish Potassium replace Flourish?
No. Flourish Potassium supplies potassium only, while Flourish provides a broader mixture of trace and minor nutrients.

Can it be used with Flourish Nitrogen and Flourish Phosphorus?
Yes. Seachem specifically notes that Flourish Potassium is suitable for use with Flourish Nitrogen and Flourish Phosphorus when targeted macronutrient dosing is needed.

Can it be used in low-tech planted aquariums?
Yes. Use it when source water, plant growth, or visible symptoms indicate that additional potassium is needed.

Is Flourish Potassium safe for freshwater shrimp?
Yes. Seachem states that Flourish Potassium is safe for freshwater shrimp, including Amano shrimp, when used as directed.

Can potassium be overdosed?
Potassium is generally tolerated across a broad range, but unnecessary overdosing can create nutrient imbalance. Follow the label dosage and adjust according to plant demand.

Does activated carbon remove Flourish Potassium?
No. Seachem states that carbon filtration does not remove Flourish Potassium from aquarium water.

Available at Tropical Treasures Wyo

Seachem Flourish Potassium 250 mL provides concentrated potassium for preventing 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, test kits, and aquascaping essentials.

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