[For beginners] How to use potassium fertilizer

This article explains “How to use potassium fertilizer”.

A lot of aquatic fertilizers will get you lost?

If you put the fertilizer in the wrong way, it will not only have an effect, but also algae will grow.

Beginners should first practice adding fertilizer from potassium fertilizer.

It is not too late to use other fertilizers.

We will give an easy-to-understand explanation of the addition amount and addition interval in an easy-to-understand manner.

If you are interested, please read it.


It is difficult to master fertilizer. Beginners should start with potassium fertilizer!

Before adding fertilizer

Aquatic plants have “Five elements” that are essential for their growth.

Fertilizer is one of them, but aquatic plants do not grow beautifully if there is not enough other elements even if fertilizer is abundant.

In particular, if fertilizer is left in excess, “algae” are likely to be generated, so care must be taken.

Let’s work on fertilizer after clearing the other four.

We assigned numbers from the ones that are easy to deal with, so it is a good idea to check from number 1.

Five elements
Five Elements“Five elements” required for aquatic plants

Why start with potassium fertilizer?

This is because potassium tends to be deficient in the tank, and algae are difficult to produce if excessively added.

Therefore, it is easy to achieve the effect and there are few failures, so beginners are advised to start with potassium fertilizer.


Just good for fertilizer practice!

Effects of potassium fertilizer

It is said to be “related to root generation”.

I am also involved in the synthesis of chlorophyll precursors required for photosynthesis.

This is especially important under low light conditions, and is especially useful when growing in low lights.

How to use potassium fertilizer

Usage is simple.

Just put “half of the prescribed amount” or “the prescribed amount” into the tank!

It is better to start with about half of the prescribed amount and increase the amount added while watching the aquatic plants.

There are two types of potassium fertilizer: “liquid type” and “tablet type”.

The result is the same regardless of which you use, so choose the one that is easy to use.

When CO2 is not added, the metabolic rate is slow, so “1/4 to 1/8 of the specified amount” is sufficient.

Liquid type

A popular type of potassium fertilizer.

Because it is liquid, it can be put in immediately and spreads throughout the tank.

Therefore, there is immediate effect.

Work is easy because it is a push pump.

Immediately effective but not persistent. Therefore, it is necessary to add frequently.

Be careful not to add too much because it is easy to add.

  • Immediately effective
  • Easy adjustment of addition amount
  • Easy to add
  • Not persistent
  • Be careful not to add too much

Addition example

” 2 weeks to 1 month ” After tank setting

You may not need to add it immediately after setting the tank.

Soil with much fertilizer ⇒ 1 month later

Soil with less fertilizer, gravel ⇒ 2 weeks later

Let’s add from such time.

Monday “addition”

Add fertilizer to the tank.

Wednesday “addition”

Add fertilizer to the tank.

Friday “addition”

Add fertilizer to the tank.

Saturday and Sunday “Work”

Perform maintenance work such as changing water, trimming, or adding aquatic plants.

Monday “addition”

It is a repetition after this.

Addition is possible at intervals of 2 to 3 days.

You do n’t have to add fertilizer on the day you work.


The day of the week is an example, so please go at a convenient time.

Tablet type

This type is used by being embedded in the substrate.

It is a good idea to fill in the tank before setting it.

The effect is sustained for a while because it gradually melts and exerts its effect.

Even if you add too much, it will not be a problem because it will be effective slowly.

Once you add water, it is hard to add fertilizer.

  • Long lasting effect
  • Fewer failures
  • Not effective immediately
  • Hard to add

Addition example

“Fill in substrate” when setting tank

When setting the tank, it is easy to put it in the substrate beforehand.

If you use gravel and soil with less fertilizer, add it.

Add if using less fertilizer soil or gravel.

1 month later “Add”

Pinch with tweezers and put it into the substrate.

Please work quickly as the fertilizer will collapse.

1 month later “Add”

Pinch with tweezers and put it into the substrate.

Please work quickly as the fertilizer will collapse.

1 month later “Add”

Pinch with tweezers and put it into the substrate.

Please work quickly as the fertilizer will collapse.

1 month later “Add”

The rest is repeat.

For tablet type, the duration of the effect varies depending on the product.

It depends on the location and depth of filling. Let’s adjust while watching the state of aquatic plants.

For bottom filter

If you use a bottom filter, the water in the substrate is good and the fertilizer may not be sustainable.

Although there are no problems, the benefits of the tablet type will be lost.

Therefore, if you are using a bottom filter, you should use only the “liquid type”.

Do you use liquid type and tablet type at the same time?

Liquid type and tablet type can be used at the same time.

Rather it is recommended usage!

It is better to bury the tablet type in the substrate in advance and make up for the missing part with the liquid type.

As the amount of aquatic plants grows, the amount of fertilizer required increases.

By using a liquid type that allows easy fine adjustment of the amount added, you can respond to subtle changes in the environment.

Is it okay to put no other fertilizer?

To maintain aquatic plants in “perfect condition” for a long period of time, it is essential to use various fertilizers.

However, it is very difficult to master fertilizers, and high skills are required.

Beginners should start with potassium fertilizer, get used to “adding fertilizer to the tank”, and try other fertilizers, so there will be fewer failures.

Nitrogen and phosphorus are supplied from fish dung and remaining food.

In addition, minerals such as calcium and magnesium are supplied from tap water by water exchange.

That alone will be insufficient when aquatic plants grow.

However, it is better than a large amount of algae due to “too much fertilizer” and “incorrect choice of fertilizer”.


Fertilizers other than potassium often produce “algae” if they are added incorrectly.

If you get used to potassium fertilizer

The next step is to get used to other fertilizers.

Let’s challenge fertilizers such as nitrogen, phosphorus, iron, and trace elements.

These fertilizers are prone to algae when they are left over.

Let’s add while consulting with the condition of the tank.

Next steps
  • Nitrogen fert
  • Comprehensive fert (various fertilizers mixed with things)
  • Trace element fert

Recommended potassium fertilizer

Here are some of the fertilizers I have used that I can recommend.

All products are effective, so feel free to use them.

Liquid type

ADA Brighty K

The most popular potassium fertilizer.

Beginners can practice fertilizer with this.

ADA Brighty K


Potassium fertilizer that does not raise the pH.

This is recommended if you are laying with aquatic plants that prefer soft water.


Tablet type

Tetra InitialSticks
Tetra InitialSticks

It is most recommended as a substrate fertilizer for potassium.

Since there are so many prescribed amounts, “about half of the prescribed amount” is sufficient.

Work quickly because it will dissolve in a short time when touched by water.

Use it on the substrate in advance when setting the tank.

Tetra InitialSticks


It is important to use fertilizer to grow aquatic plants beautifully, but it is very difficult to use fertilizer.

However, if you can make full use of fertilizer, you can grow aquatic plants more beautifully.

Start with potassium and get used to various fertilizers.


Please be careful not to put too much fertilizer!