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10 US gal · 37.9 L

Fertilizer calculator for a 10 gallon planted tank

Exact doses for a 10 US gallon tank (37.9 liters), computed with the same engine as the dosing calculator. Open it prefilled to change light level, water change or substrate volume.

Open the 10 gal EI calculator10 gal stock solution

Dry dosing: grams per dose for 10 gallons

Weigh each salt on a 0.01 g scale and add it straight to the tank. EI and lean EI split the weekly amount into 3 macro doses and 3 micro doses on alternate days; low-tech is one dose a week. Numbers assume the full 37.9 L; if substrate and rock take 15 % of the space, multiply by 0.85.

SaltEI (per dose, 3×/wk)Lean EI (per dose, 3×/wk)Low-tech (once a week)
KNO₃ (potassium nitrate)0.463 g (463 mg)0.247 g (247 mg)0.309 g (309 mg)
KH₂PO₄ (monopotassium phosphate)0.054 g (54.2 mg)0.027 g (27.1 mg)0.027 g (27.1 mg)
K₂SO₄ (potassium sulfate)0.41 g (410 mg)0.192 g (192 mg)0.138 g (138 mg)
MgSO₄·7H₂O (Epsom salt)0.768 g (768 mg)0.384 g (384 mg)0.384 g (384 mg)
CSM+B (trace mix)0.116 g (116 mg)0.058 g (58 mg)0.058 g (58 mg)

Weekly targets used (ppm added per week): EI NO₃ 22.5, PO₄ 3, K 30, Mg 6, Fe 0.6; lean EI about half; low-tech NO₃ 5, PO₄ 0.5, K 5. K₂SO₄ only tops up potassium that KNO₃ and KH₂PO₄ don't already supply. The CSM+B amount assumes a typical 6.53 % iron label; check your bag.

With EI and a 50 % weekly water change, nitrate settles at about 45 ppm just before each change (weekly dose ÷ 0.5). Change less water and it climbs higher; see how water changes affect dosing.

Stock solution recipe for a 10 gallon tank (500 mL bottles)

Dissolve in distilled or RO water, top up to 500 mL, and dose 42 mL per dose (the bottle lasts about 4 weeks at 3 doses a week). Keep macros and micros in separate bottles.

BottleDissolve in 500 mL
Macro (EI)5.58 g KNO₃ + 0.654 g (654 mg) KH₂PO₄ + 4.94 g K₂SO₄ + 9.25 g MgSO₄·7H₂O
Micro (EI)1.4 g CSM+B

All salts stay well under their solubility limits at this strength. Some keepers move MgSO₄ to the micro bottle or dose it dry; see where MgSO₄ goes and how to make a stock solution.

Liquid fertilizers: label doses for 10 gallons

ProductLabel dose for 10 galHow often (label)
Seachem Flourish0.8 mL5 mL per 250 L (60 US gal) once or twice a week
Seachem Flourish Nitrogen0.6 mL2.5 mL per 160 L (40 US gal) twice a week
Seachem Flourish Phosphorus1.2 mL2.5 mL per 80 L (20 US gal) once or twice a week
Seachem Flourish Potassium1.5 mL5 mL per 125 L (30 US gal), 2–3 times a week
Tropica Specialised Nutrition4.5 mL6 mL (3 pumps) per 50 L once a week at the water change
Tropica Premium Nutrition4.5 mL6 mL (3 pumps) per 50 L once a week at the water change

Scaled linearly from each maker's directions. Seachem Flourish at 0.8 mL adds about 0.064 ppm iron; Tropica Specialised at 4.5 mL a week adds about 6.91 ppm nitrate-equivalent. Compare products in the product library.

FAQ

How much KNO3 do I dose in a 10 gallon tank?

For EI, about 0.463 g (463 mg) per dose, three times a week (22.5 ppm NO₃ a week). Lean EI is about 0.247 g (247 mg) per dose. A low-tech tank needs about 0.309 g (309 mg) once a week.

How much KH2PO4 for a 10 gallon planted tank?

About 0.054 g (54.2 mg) per dose for EI (3 ppm PO₄ a week over three doses) and 0.027 g (27.1 mg) for lean EI.

How much Seachem Flourish for a 10 gallon tank?

Seachem's directions are 5 mL per 250 L (60 US gal) once or twice a week, which is about 0.8 mL for 10 gallons. Each cap thread is about 1 mL.

How much Tropica Specialised Nutrition for 10 gallons?

Tropica recommends 6 mL (3 pumps) per 50 L each week at the water change, so about 4.5 mL (2.3 pumps) a week for 38 L.

Should I dose for the full tank volume?

Dose for the water actually in the tank. Substrate, rock and wood often take 10 to 25 % of the nominal volume, so many people dose for about 85 %. Under-dosing slightly is safer than over-dosing, especially with shrimp.

Other tank sizes

20 gallon29 gallon40 gallon55 gallon75 gallon125 gallon

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