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MasterLine Phosphate – PO4 & Potassium Liquid Fertilizer for Planted Aquariums (500ml / 1000ml)

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Trusted by 500+ aquascapers

€6,66
  • Phosphate dosed independently
  • 1 ml per 30 L adds about 0.5 ppm PO4
  • Built for EI-style separate dosing
  • Tops up an all-in-one when PO4 runs low
  • Also supplies a little potassium

Phosphate on its own, for anyone who doses by test results rather than trusting one all-in-one bottle. A millilitre per 30 litres lifts PO4 by roughly 0.5 ppm, so you hold it exactly where your plants grow best.

Size

Fast delivery (1–5 days EU)

Carefully packed and protected

Tips from real aquascapers

Description

MasterLine Phosphate — Precision PO4 & Potassium Fertilizer for Planted Tanks

MasterLine Phosphate is a single-component liquid fertilizer that supplies phosphorus in the form of phosphate (PO4), along with potassium (K), two of the essential macronutrients aquatic plants need for healthy growth. Unlike all-in-one fertilizers, it lets you dose phosphate independently — critical for aquascapers running an "Estimative Index" or separate-dosing regimen who want full control over each nutrient.

Why dose phosphate separately?

In tanks with an active (nutrient-rich) soil substrate, a large share of phosphate is captured and stored in the substrate, where plant roots absorb it directly — leaving very little measurable in the water column (typically only 0.1–0.2 ppm). In tanks with inert substrate, phosphate must be dosed directly into the water column. Either way, keeping PO4 too low can limit plant growth, while dialing it in precisely — rather than guessing with an all-in-one blend — gives you far more control over growth rate and algae pressure.

Dosing

1 ml per 30 liters raises phosphate by approximately 0.5 ppm PO4 and potassium by approximately 0.2 ppm K. Dose according to test results — for inert substrates, avoid letting PO4 drop below roughly 0.2 ppm; for active substrates, water column readings of 0.1–0.2 ppm are normal and not a sign of deficiency.

How to use

  • Test your aquarium's phosphate level before dosing
  • Shake well before use
  • Dose daily or as needed based on test results
  • Can be combined with MasterLine Nitrate and Potassium for a full separate-dosing regimen, or used to top up an All-In-One fertilizer
  • Store at room temperature, away from direct sunlight and frost

Best for

  • Aquascapers using separate-nutrient (EI-style) dosing
  • Planted tanks showing phosphate-deficiency symptoms (stunted new growth, dark older leaves)
  • Fine-tuning nutrient ratios to control algae in CO2-injected tanks

Specifications

Active nutrients Phosphate (PO4), Potassium (K)
Dosing ratio 1ml / 30L ≈ 0.5 ppm PO4 + 0.2 ppm K
Sizes 500 ml, 1000 ml
Compatibility Safe for shrimp and all common aquarium life when dosed correctly

FAQ

Do I need this if I already use an All-In-One fertilizer?
Only if your test kit shows phosphate running low — MasterLine Phosphate can top up an All-In-One in specific cases, or be used for full separate-nutrient control.
Is it safe for shrimp?
Yes, when dosed according to instructions it's compatible with shrimp and other invertebrates.
Why is my water column phosphate reading so low even after dosing?
Active soil substrates absorb most of the phosphate for root uptake, so column readings of 0.1–0.2 ppm are expected and not a sign the product isn't working.

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    Delivery to all EU countries

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  • Easy returns

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