Optimal amount of CO2 added to aquatic plants

Optimal amount of CO2 added to aquatic plants

In this article, we will explain about “CO2 addition optimal for aquatic plants”.

Everyone, how much CO2 is added to the aquarium?

In fact, just adding CO2 does not mean that aquatic plants grow!

Only after adding the proper amount will it be effective.

  • I’m using a CO2 addition kit, but the aquatic plants are in a bad condition..
  • It will not be like aquatic plants as seen in the contest…

Such a person may not have enough CO2 added.

If you read this article, anyone will be able to understand the “ CO2 addition optimal for aquatic plants ” in any tank.

It will be explained to beginners in an easy-to-understand manner, so please read it.

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Genki

Read this article and graduate from “Aquatic plants beginner”!

How to measure the amount of CO2 added

To know the appropriate amount of CO2, first let’s know “appropriate measurement method”.

That’s easy.

Just look at the “CO2 counter” that comes with the CO2 addition kit.

It counts like “How many bubbles are coming out per second”.

The expression “1 second / 1 drop” often found in magazines, etc., represents this.

If you hear 1 second / 1 drop, it will follow the bubble and count, but it is easier and more accurate to measure “how many drops are in 10 seconds?”

The Appropriate amount of CO2

TankLow lightHigh light
15L3 sec / 1 drop 2 sec / 1 drop
30L2 sec / 1 drop 1 sec / 1 drop
60L1 sec / 1 drop1 sec / 1 ~ 2 drop
100L1 sec / 2 drop 1 sec / 2 ~ 4 drop
150L1 sec / 3 drop 1 sec / 3 ~ 4 drop
300L1 sec / 4 drop 1 sec / 5 ~ 7 drop
650L1 sec / 8 drop 1 sec / 9 ~ 15 drop

Approximate. Please use as a guide as it varies depending on the situation

This is a table that summarizes the amount of CO2 added according to the amount of water.

First of all, please adjust the amount of addition using this table.

Low light

This is the amount of tanks added mainly to aquatic plants such as Microsorium , Anubius, and Cryptocoryne that grow even in dark environments.

If you are planting mainly aquatic plants classified as “easy plants”, please refer to the amount added here.

High light

This is the amount of tanks that are mainly made from plants that grow like carpets, such as aquatic plants, Rotara, Ludwigia, and Pearl grass that are repeatedly trimmed to make bushes.

If you want to make a full-fledged aquascape tank, please refer to the amount added here.

It ’s added like the table but it does n’t grow up?

If aquatic plants do not grow even though they are added well, the water quality may not be right.

In fact, if the added CO2 is pH 6.5 or higher, aquatic plants cannot be used effectively.

pH 6.5 or less

If you want to grow beautiful aquatic plants, adjust the pH to 6.5 or less (details will be explained later).

This is very important.

Are you thinking of adding CO2 but adding fertilizer because aquatic plants don’t grow beautifully?

wait a minute.

Let’s check the water quality before adding fertilizer.

If the water quality does not match, fertilizer will not work because the fertilizer absorption efficiency is poor.

There are five important elements in aquatic plants. If these balances are not good, it will not grow neatly and it will become a tank where a lot of algae grow.

We have explained in detail about “Five elements” and “Optimal water quality” here.

Five Elements“Five elements” required for aquatic plantsOptimal water qualityOptimal water quality for Aquascape Tank

CO2 addition optimal for “accurate” aquatic plants

TankLow lightHigh light
15L3 sec / 1 drop 2 sec / 1 drop
30L2 sec / 1 drop 1 sec / 1 drop
60L1 sec / 1 drop1 sec / 1 ~ 2 drop
100L1 sec / 2 drop 1 sec / 2 ~ 4 drop
150L1 sec / 3 drop 1 sec / 3 ~ 4 drop
300L1 sec / 4 drop 1 sec / 5 ~ 7 drop
650L1 sec / 8 drop 1 sec / 9 ~ 15 drop

In fact, most of the aquatic plants can be grown beautifully if they are added at pH 6.5 or less and as much as this table.

However, we will also explain how to know the correct amount of CO2 for later study. If you are interested, please read it.

Knowing the appropriate amount of CO2 from pH and KH

First, you need to know the relationship between pH and KH to know the correct amount.

There is a cumbersome formula when actually calculating, but now it can be easily found by searching.

If you search for “pH KH correlation”, you can see various information.

CO2 addition chart

This is the “CO2 addition chart” I made from the correlation diagram of pH and KH.

This is a modified version of a common correlation diagram, based on my experience.

I think that adding more CO2 will give better results, so I set it one step higher than what is generally known.

Let’s use this chart to find the right amount of CO2.

Since it is not familiar, I will be a little confused, but I will explain it step by step.

First, look at the flowchart for checking the amount of CO2 added.

Measure pH and KH

Use a pH meter, KH measurement kit, etc. to measure the water quality.

エコPH
Check against the chart

Calculate CO2 from the measured pH and KH.

Best if you are in the green area.

Adjust water quality and CO2 addition

If it is not the right value, adjust the water quality and the amount of CO2 added to get the right value.

Repetition

The following is repeated from STEP1.

If you’re doing it as usual but the aquatic plants don’t grow up well, be sure to put a habit of checking the water quality.

In many cases, the pH is high and aquatic plants cannot absorb CO2.

Next is how to read the chart.

The yellow part of the chart is pH, the blue part is KH, and the point where each crosses is the CO2 concentration.

The CO2 concentration is expressed in this way.

  • Green best
  • Purple OK for easy aquatic plants
  • White CO2 shortage
  • Red CO2 excess

Using this chart, you can easily know the appropriate amount of CO2.

e.g. 1

If pH6.8, KH3, CO2 is 18mg / ℓ → CO2 shortage

Increase the amount of CO2 added until the pH reaches 6.5-6.6.

e.g. 2

pH 7.0, KH8, CO2 is 30mg / ℓ → CO2 amount is OK, water quality is not right

Since both pH and KH are high, CO2 cannot be used for photosynthesis, so let’s lower pH and KH

For a typical aquascape tank

・ PH = 6.0 ~ 6.5
・ KH = 1 ~ 4

You can use this area as a guide.

The current situation is that there are many people who do not have enough CO2 added.

If you feel that the growth of aquatic plants is bad, please measure the water quality and adjust the amount added.

The Relationship between pH and CO2

I think that knowing this will change the consciousness of water quality.

It’s strange, but CO2 is more sensitive to pH than aquatic plants than fish.

If you write the conclusion first

pH = 6.5 or less

This makes it easier for aquatic plants to use CO2.

It is for this reason that it is said that “aquatic plants’ favorite water quality = Mild acidity”.

The nature of CO2

Let’s take a look at the chart again.

If the pH is higher than pH 6.7, the reason for the purple area even if the CO2 concentration is sufficient is due to the nature of CO2.

CO2 dissolved in water is divided into “free carbonic acid (CO2)” and “bicarbonate ion (HCO3-)”.

It is pH that determines the ratio.

Basically, aquatic plants are used for photosynthesis from free carbonic acid, and when there is little free carbonic acid, hydrogen carbonate ions are used for photosynthesis.

Therefore, aquatic plants cannot use CO2 effectively at high pH, no matter how high the CO2 concentration is!

ATTENTION
However, aquatic plants originally grown in areas with low KH (such as tropical aquatic plants) do not have the ability to use bicarbonate ions for photosynthesis, so if pH is high, no matter how much CO2 is added, it becomes difficult to grow.

Graph of free carbonic acid and bicarbonate ion

This is a graph of the ratio of free carbonic acid to bicarbonate ion.

“Blue bar graph is free carbonic acid” and “red line is hydrogen carbonate ion”. The vertical axis represents% and the horizontal axis represents pH.

Free carbonic acid and bicarbonate ions are halved at pH 6.37, and the proportion of free carbonic acid decreases with increasing pH.

In other words, when the pH is high, even if a lot of CO2 is added, aquatic plants cannot be used for photosynthesis.

At pH 7.0, the ratio of free carbonic acid is about 20%, but at pH 6.0, about 70% can be used as free carbonic acid. There is a difference of 50%.

POINT
Easy aquatic plants naturally grow in places where the pH is high and bicarbonate ions exist. Therefore, the body is made to use bicarbonate ions for photosynthesis. However, since easy aquatic plants are also used for photosynthesis from free carbonic acid, it will grow beautifully when CO2 is added.
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Genki

It is also possible to reduce the amount of CO2 added by lowering the pH and increasing the proportion of free carbonic acid.

You can save on CO2 and easy on the wallet !

Check water quality, adjust water quality

Let me introduce what I am using.

What is sold by country is different.

If you can’t get what you want to introduce, substitute one that you can buy nearby (Maybe sold on Amazon).

Measure water quality

Tetra Test pH
Tetra Test pH

Check the pH by changing the color of the reagent.

It can be measured as acidic, mild acidic, neutral, mild alkaline, or alkaline.

If it is an aquarium with strong aquatic plants, it is practically enough. It is an entry model for water quality inspection.

Beginners can use it to get a sense of measuring water quality. If you want to make a full-fledged aquatic aquarium, I recommend a pH meter. I no longer use this.

Tetra Test pH

pH meter

The pH can be measured in increments of 0.1 in the same way as a digital thermometer.

It can be measured more easily than the reagent type and is accurate.

If you want to make a full-fledged aquascape aquarium, you should have it.

Search for “pH meter” on Amazon.

Tetra Test KH
Tetra Test KH

Check the pH by changing the color of the reagent.

Count how many drops of chemical change occurred and measure the number of drops as dH.

This is the KH measurement drug that is easily available at the aquarium shop.

Since this one box can be used for several years, I have only used it.

Tetra Test KH

ADA Drop Checker

If you put the attached reagent in a round part and install it in the water tank, the color of the chemical will change according to the amount of CO2 added.

Excessive / yellow
Appropriate amount / green
Shortage / blue

In this way, the chemical solution changes.

You can check it intuitively without troublesome measurement work. The design is also wonderful.

My favorite among many ADA products.

*Since the ratio of free carbonic acid and hydrogen carbonate ions cannot be determined, measure the pH!

ADA Drop Checker

Adjust water quality

Tetra pH/KH Minus

If you manage an aquascape aquarium, you want to have it.

The pH and KH can be lowered by adding it when changing water.

When you get used to it, you may be able to put it directly into the tank, but it is common to draw tap water into a bucket and adjust the water quality there before putting it in the aquarium.

In general, the standard amount is about 10L / 1ml (when pH is 7.0 or higher).

Since it is a highly acidic chemical, use a pH meter little by little.

Tetra pH/KH Minus

The Summary

pH 6.5 or less

After adjusting the water quality, adjust the addition amount with reference to this table.

TankLow lightHigh light
15L3 sec / 1 drop 2 sec / 1 drop
30L2 sec / 1 drop 1 sec / 1 drop
60L1 sec / 1 drop1 sec / 1 ~ 2 drop
100L1 sec / 2 drop 1 sec / 2 ~ 4 drop
150L1 sec / 3 drop 1 sec / 3 ~ 4 drop
300L1 sec / 4 drop 1 sec / 5 ~ 7 drop
650L1 sec / 8 drop 1 sec / 9 ~ 15 drop

The “appropriate amount of additive” varies slightly depending on the environment.

After that, you can adjust it while watching the aquatic conditions.

If pH is 6.5 or less, you should be able to feel the effect of adding CO2, so if you look closely at the aquatic plants, you will notice subtle changes.

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Genki

I pray for your aquatic plants to grow beautifully!