Seachem Flourish Potassium – Pure Potassium Supplement for Planted Tanks

Fix Potassium Deficiency Without Touching Your NPK Balance

Potassium is easy to deplete in a fast-growing tank or with mineral-poor source water, and when it runs low it becomes the limiting factor on growth, showing up as yellowing in older leaves. Most potassium sources also add nitrogen or phosphorus, wrecking your carefully tuned NPK ratio.

Seachem Flourish Potassium contains 50,000 mg/L of potassium derived from potassium sulfate, so you can raise potassium levels without affecting nitrogen or phosphorus. That lets you target a precise NPK ratio and keep growth vigorous, something potassium nitrate or potassium phosphate sources simply can't do.

Flourish Potassium is formulated by Seachem Laboratories, the chemistry-driven aquatics company founded in 1979 in Madison, Georgia, where in-house chemists develop each product. It's the potassium component of the coordinated Flourish planted-tank system, one of the targeted macro (NPK) supplements that pair with the comprehensive Flourish supplement, Flourish Excel for carbon, and iron and trace dosing.

1. Dose Flourish Potassium to prevent depletion in rapidly growing or low-mineral systems.
2. Watch for yellowing older leaves as the sign more potassium is needed.
3. Adjust potassium independently while keeping your nitrogen and phosphorus on target.

Dial in potassium precisely and keep your plants growing strong. Add to cart.

What It Does

Contains 50,000 mg/L of potassium for the natural planted aquarium. Derived from potassium sulfate, it lets you adjust potassium levels without affecting nitrogen or phosphorus, making it possible to target a specific NPK ratio. Prevents potassium depletion, a sign of which is yellowing in older leaves.

Ingredients

Derived from: Potassium sulfate. Elemental potassium is present at a concentration of 50,000 ppm (e.g. 5%). Fertilizer laws require potassium to be listed in terms of equivalence to K2O rather than simple elemental equivalence.

Why Seachem Flourish Potassium

• Potassium macro of the Flourish system: supplies the K in NPK so you can dose potassium precisely alongside Flourish Nitrogen and Phosphorus and the comprehensive Flourish supplement.
• Clean potassium-sulfate source: raises potassium in a bioavailable form without adding nitrogen or phosphorus, unlike potassium nitrate or potassium phosphate sources.
• Fixes potassium deficiency: restores the potassium that runs low in fast-growing or mineral-poor tanks and shows up as yellowing in older leaves.
• Highly concentrated: 50,000 mg/L (5%) of elemental potassium, letting you target a precise NPK ratio.

Best For

Ideal for high-tech, fast-growing planted tanks and setups on mineral-poor or RO/soft source water where potassium drops quickly. Best for aquarists tuning a specific NPK ratio who need to raise potassium independently, and for tanks showing yellowing or pinholes in older leaves.

FAQ

Will this change my nitrogen or phosphorus levels? No. It's derived from potassium sulfate, so it adjusts potassium without affecting nitrogen or phosphorus, letting you target a specific NPK ratio.

What does potassium deficiency look like? A common sign is yellowing in older leaves, which indicates the tank needs more potassium.

How does this fit with the rest of the Flourish line? Flourish Potassium is the potassium macro in Seachem's coordinated planted-tank system, used with Flourish Nitrogen and Phosphorus plus the comprehensive Flourish supplement, Flourish Excel for carbon, and iron and trace dosing.