Delivery throughout the EU
1 2

MasterLine Potassium

Trusted by 500+ aquascapers

€6,66
  • Fixes brown and yellow leaf margins
  • Pure potassium, nothing else added
  • Dose by test, not by guesswork
  • Works alongside any fertiliser brand
  • Safe for shrimp and sensitive fish

Brown or yellow edges creeping in on otherwise healthy leaves are the classic potassium sign. A single-element supplement lets you top potassium up when a test reads under 15 ppm, without adding nitrate or phosphate you did not ask for.

Size

Fast delivery (1–5 days EU)

Carefully packed and protected

Tips from real aquascapers

Description

MasterLine Potassium is a pure potassium (K) supplement for planted aquariums. Potassium is the third most important macronutrient for aquatic plants and is essential for enzyme activation, water regulation within plant cells, and overall metabolic function. Deficiency causes brown or yellow leaf edges and reduced growth. MasterLine Potassium is dosed as needed when potassium levels in the aquarium fall below 15 ppm.

Key benefits

  • Pure potassium supplement — precise single-element control
  • Prevents and corrects potassium deficiency (brown/yellow leaf margins)
  • Compatible with all fertilization systems — use alongside any brand
  • Safe for shrimp and sensitive fish

When to use

Dose when potassium levels drop below 15 ppm, as measured with a potassium test kit, or when plants show signs of deficiency. Particularly useful in high-light, high-growth aquariums where potassium is rapidly consumed.

Pair with

  • MasterLine Nitrate — nitrogen supplement
  • MasterLine Phosphate — phosphorus supplement
  • MasterLine I — micronutrient formula

  • Professional support

    Expert help when you need it

  • Delivery throughout the EU

    Delivery to all EU countries

  • Secure payment

    Fast and secure payment options

  • Easy returns

    Лесно връщане и замяна
​

FAQ

What makes Aquarium Boutique different from mass-market stores?

We don't sell everything — we sell only carefully selected products, personally tested. Every item is chosen with a clear purpose: to work well and last long. You don't need to guess about quality — we've already done that for you.

Do you ship to my country?

Yes, we ship across all of Europe. For Bulgaria we work with BOX NOW and Speedy — fast and reliable home or locker delivery. For other EU countries we use international courier services.

How quickly will I receive my order?

For orders within Bulgaria, we typically deliver within 1–3 business days. For other EU countries — usually 3–7 business days depending on location.

Can I return a product if I'm not satisfied?

Yes. If something doesn't meet your expectations — contact us. We have a clear and fair return policy. Your satisfaction matters to us and we will find a solution.

Do you offer advice on product selection?

Absolutely. Our team keeps aquariums and knows the products personally. Write to us — we'll help you choose the right solution for your tank, budget and experience level.

Are your products tested and approved?

Yes. Every product in our store has gone through our personal selection and testing process . We only work with trusted brands and don't list products we don't believe in.

What payment methods do you accept?

We accept all major payment methods — credit and debit cards, PayPal, and cash on delivery for Bulgaria. All payments are secure and encrypted.

How can I track my order?

After your order ships, you'll receive an email with a tracking link. You can follow the status in real time directly through the courier's website.