How to fight and prevent thread algae in your aquarium?

Have you been aquascaping for a while? If so, you’re going to recognize this. You’ve surely seen those ugly green thread algae that stick to the edges of the leaves of your aquarium plants and eventually choke them.

In no time, these terrible aquarium string algae grab everything around them. You have to act upon them, and quickly, or those green thread algae will proliferate at a dazzling speed and the situation will get even worse. And then, your aquarium will be in trouble.
So, what’s the quickest way to get rid of those string algae in your aquarium? By looking for their cause and having a plan of action.

This is what this article is about.

What is the cause of thread algae?

So, do you have green thread algae in your aquarium?

You’d better act quickly then ;-). That’s why I’m keeping it short. There’s only one cause of thread algae: a lack of CO2.

If your aquarium lacks CO2, it can be because you don’t add enough of it (or not at all). Or maybe your lighting is way too high. In fact, the more light you put above your aquarium, the faster your plants grow and the more nutrients they need, including CO2.

How to get rid of thread algae in your aquarium?

There are 2 targeted ways to fight against those green string algae.

The first way is to tackle this CO2 deficiency by adding enough nutrients. The second way is to adjust the intensity of your lighting to match with the amount of CO2 you add.

Nutrients are the easy part, so I will come back to them later. Ending a CO2 deficiency is easier said than done, but these tips should help you to get rid of those hair algae in your aquarium. Let’s begin!

1) Eliminating thread algae with a CO2 system

In this case, you tackle the green thread algae problem by increasing the CO2 in your aquarium, slowly but surely.

I have a reason for insisting on “slowly”. If you increase your CO2 too fast, it can be dangerous for your fish. That’s why I wrote this article, in which you can learn the best way to do so.

So, you increase your CO2 very carefully, maximum once per week, to avoid any fluctuations. Then, you wait for about two weeks, to see the reaction of your aquarium plants and check out the behavior of the fish.

Are your plants growing better? Are the green thread algae slowly disappearing? Great, you are on the right track. Do you still have thread algae? I would advise you to increase your CO2 a little more, very carefully, while keeping an eye on your fish.

2) Eliminating thread algae without any CO2 system

If you don’t have a CO2 system, you cannot just increase your CO2. So, there’s actually only one way to get more CO2 into your aquarium: making sure that your aquarium gets less light. By using less intense lighting, you slow down the photosynthesis of your plants. So they grow more slowly and as a consequence, they ask for less nutrients, including CO2.

As a result, the CO2 deficiency of your aquarium silently disappears, and the green string algae disappear with it!

3) My favorite way: a combination of both

What is the most effective method? It is the combination of the tips above. You slowly increase the CO2 while decreasing the lighting at the same time. After about two weeks, you will see that the thread algae have significantly diminished. Meanwhile, try to manually remove as much as possible, and it will be alright.

How about plant nutrition?

Now that you’ve tackled the CO2 deficiency of your aquarium, it is important to make sure that your plants get enough nutrients. This way, you can ensure that any bad growth of your plants won’t be due to a lack of nutrients. Here are a few symptoms of nutrient deficiencies in aquarium plants.

So, besides CO2, what kind of nutrients do you actually have to give your plants? The most important nutrients are the so-called “macronutrients”: nitrogen, phosphorus and potassium. In addition, there are “secondary nutrients”, such as magnesium, and “micronutrients” (or “trace elements”) such as iron, manganese, …

Does this sound like a lot of work?

Well, it’s much easier if you use my All-in-One fertilizer. It actually contains all those nutrients in just one bottle, so you no longer need to buy 4 or 5 different bottles. It turns out much cheaper on the longer term, and it is much easier to add to your aquarium. Especially if you are a little lazy like me. 😉

How to prevent any green thread algae from now on?

Make sure you have the right balance between the amounts of light, CO2 and nutrients in your aquarium. A little trick I use: keep the lights down low until you’ve got the CO2 and nutrients under control.

Is it looking good? Then, and only then, you start increasing the lighting, slowly. Keep an eye on your plants and act upon the slightest bit of green thread algae. You can remove any thread algae with a toothbrush and increase the amount of CO2 a tiny little bit at a time. You need to work very meticulously, to get your aquarium entirely free of those green string algae!

Conclusion

You’re better off without those green thread algae in your aquarium, so it is crucial to act quickly. If you don’t want to be continuously on the lookout armed with a toothbrush, make sure you tackle the problem by eliminating the cause. And the cause is simply… a CO2 deficiency!

The best method is:

• Carefully increasing the CO2 with a good CO2 system
• Slightly decreasing the light intensity if possible
• Continuously giving a good aquarium plant fertilizer

After about two weeks, you will already notice a big difference. Do you have a story to share or some extra tips to eliminate or prevent thread algae? Feel free to share in the reactions below.