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Seachem Flourish Excel Review

If you are interested in building a planted aquarium you need to start by taking one important decision. You have to plan whether you want to go ‘low tech’ or ‘high tech’.

In a ‘high tech’ aquarium a pressurized CO2 system is introduced. Many people do not consider this an attractive option and thus decide to go ‘low tech’.

Yes, the ‘low tech’ approach does have a few benefits but there is a far better option.

Wouldn’t it be great if you have something between slow growth and a complete CO2 setup?

It is indeed possible with the help of a solution known as Flourish Excel from a brand called Seachem.

We shall learn more about this product through this Seachem Flourish Excel review.

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What is Seachem Flourish Excel?

Flourish Excel is among the most popular liquid carbon available. It has been created by the famous aquarium hobby brand, Seachem.

Remember, it is not possible for you to replace a conventional CO2 system using Flourish Excel.

Nonetheless, if you use the right dose, it will help you grow aquarium plants in a great way.

Through this Seachem Flourish excel review, you will get to learn about my experience with this wonderful solution.

Also, you will discover a few problems that I faced. This is my experience and you can follow it for sure.

However, the results may not be identically the same and so you may need to experiment a bit.

What will be the ideal time to use Flourish Excel?

According to the manufacturer of Flourish Excel, you can dose it whenever you want. I, however, will suggest adding it to your tank soon after the lights are turned on.

The plants use Flourish Excel during photosynthesis. You surely are aware that plants photosynthesize when they get nutrients and light.

During this stage, CO2 will be absorbed by the plants through the leaves and oxygen will be released.

In the absence of light, plants begin consuming oxygen and release CO2. If you add Flourish Excel at this stage, it will be of no use.

Plants will not be able to absorb it and it will be almost wasted.

Clearly, if you are interested in the best results, add Flourish Excel soon after the lights are turned on.

How frequently should you dose Flourish Excel?

[amazon link=”B000256962″ title=”Flourish Excel” link_icon=”amazon” /] starts breaking down in the tank water within 24 hours. So, post 24 hours it will not be effective anymore.

Many people add a dose of Flourish Excel thrice a week or every alternative day. This, according to me, does not work great.

I started dosing Flourish Excel every day and it is then that I got satisfactory results.

If you dose it every alternative day then it may result in the development of black beard algae, a problem I had also faced.

This type of algae grows in tanks with CO2 fluctuations. So, if you do not want to attract black beard algae, dose Flourish Excel every day.

What will be the ideal dose of Flourish Excel?

Whenever you use any product for your aquarium you should follow the instructions given on the label and this case is no different.

The label suggests 5 ml of Flourish Excel be added to 200 liters of water every day.

Once there is a change in the water the dose can alter. You can then add 5 ml of the solution to 40 liters of water.

This recommendation did not work well for me. I did not notice good plant growth, instead, black beard algae started to conquer.

So, I decided to experiment and increased the dose. I am using the solution in a 240-liter tank.

Since I have lava rocks and thick substrate the volume of the water is less than 240 liter.

My tank has fast as well as slow-growing plants. The light remains on for about 8 hours each day and I use liquid fertilizer regularly.

I feed once ever day, add iron once a week, and I do not have a heavily stocked aquarium.

This is how I dose my aquarium

  • 5 ml on the first two days
  • 7 ml on the third and fourth day
  • 10 ml on the fifth and sixth day
  • 12 ml from seventh to the tenth day
  • 15 ml from eleventh to the fifteenth day

As you can see I began by using the suggested dose. I then kept increasing the dose slowly not to shock my plants.

Just after one week, my tank was receiving double the suggested dose.

It did bring about a great change. the plants began growing really well. Even the slow-growing plants like Java Fern began growing a few leaves instantly. Also, Crypts and Swords started gaining power.

There was an even amazing development in the fast-growing plants. Guppy grass, bacopa, and water wisteria began growing by an inch each day.

Algae started dying after 12 days. At this stage, I maintained the current dose, which is 15 ml of the solution.

Yes, overdosing can be risky so you need to be careful. It worked positively for me but you still need to go slow and be cautious.

Points to keep in mind when giving a dose

As a part of this [amazon link=”B000256962″ title=”Seachem Flourish Excel” link_icon=”amazon” /] review it is important to share with you a few points to remember when dosing this solution.

1. Amount and Kind of Plants

It is very important to be aware of the amount and types of plants when planning a dose. If your tank has many plants it will need lots of CO2.

Those who have lots of fast-growing plants have to be watchful of the dose. The amount that is recommended on the Flourish Excel label will not likely be enough.

On the other hand, if you have just added slow-growing plants then the amount mentioned on the label can be too much. This is because CO2 gets absorbed by slow-growing plants quite slowly.

If your tank has just a few plants then the suggested dose can even kill all of them.

2. The Aquarium’s Water Volume

It is crucial to find out the volume of water in your tank before you use Seachem Flourish excel. This is all the more important if you have a small tank.

0.5 ml of the solution will be ideal if you have a 20-liter aquarium. using a syringe will be safe as it helps you use the exact amount.

If you have a small aquarium, then begin by adding less than the suggested dose. you can keep increasing gradually until you have added the recommended dose.

3. Plant Fertilization

Plants require other nutrients apart from CO2. You can use liquid fertilizers and root tabs. Remember to use only those fertilizers which are healthy for tank life.

In the absence of the right nutrients, absorbing CO2 will become difficult for your plants.

Furthermore, your plants will experience a deficiency of nutrients and will eventually die. the dead plant will turn into nitrates and ammonia and algae will begin using them.

Everybody has to invest some patience and time to figure out the ideal amount of liquid carbon and fertilizers. So, you need not panic.

Yet, you should always add smaller doses first. If you underdose, it will not cause much of an issue. You can anyway always add later on.

Keep increasing gradually and see what works best for your tank.

Will algae die if there is an overdose?

The answer is yes, Flourish Excel kills algae and if overdosed, plants perish as well. Use it in huge  quantities and your fishes will also die. So, you need to be very careful with overdosing.

Do not expect any overnight results with your algae. You still can follow some tricks and enjoy quicker results.

Use Flourish excel just the way you use any medications or fertilizers for your tank. This, however, is a slow procedure.

If you want quicker results, you can use the solution for spot treatment. Take a syringe and draw the amount you require.

Now, inject it on those places where algae have developed. Within 2 days, you will start noticing positive changes.

Video: “Flourish Excel vs. Black Beard Algae”

Different quantities/bottles of Flourish Excel

If you have a small tank you can invest in a 100 ml bottle of Seachem Flourish Excel. Bottles of 250 ml and 500 ml are also available.

You may opt for them if you have a big tank or if you have already used the solution and are satisfied.


  • Helps in faster plant growth compared to non-Excel, non-CO2 tanks.
  • It is easy to use compared to creating a complete CO2 system.
  • It offers great success if you are battling with algae.


  • Can be toxic if overdosed, so you need to be careful while using it.

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To conclude this Seachem Flourish Excel review it can be said that this solution works for sure. However, there will not be overnight results.

So, you need to be patient. Quite soon you will notice your plants will growth, the problem of algae is completely controlled and your fish tank looks amazing.

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Aaron Boyd
Aaron Boyd

Hello, I’m Aaron Boyd, the proud owner and author behind Aqua Movement. I hope my article was able to answer your questions. If you want to learn more about me, click the home icon above.

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