Eliminate And Prevent Algae In Cannabis Hydroponics
3 min

Eliminate And Prevent Algae In Cannabis Hydroponics

3 min
Growing Seedshop

Algae can present a formidable threat to your hydroponic growing system. Here's how you can identify the problem and take care of it fast.

Algae is an integral part of our ecosystem and life as we know it, but algae and cannabis don't mix! Having algae appear and infest your hydroponic cannabis grow can be detrimental. We take a look at at what it is and how you can prevent it.

What Are Algae, And How Does It Develop?


While some might think of the sea when we talk about algae, you might be surprised to learn that hydroponic systems can host them as well. What about algae makes this possible, though? Let's consider the definition. Algae are particular types of “simple” plants that live in water and have no stems, leaves, or roots. All they need to thrive is water to live in, nutrients, warmth, and light. Unfortunately, this makes your hydroponic growing setup a prime destination for them to build up, especially in your reservoir.

What Is The Impact Of Algae On Cannabis?


But what's the problem, you might wonder? It looks harmless, sure, but there's something happening beneath the face. Remember: this is another plant growing in the same nutrient solution as your cannabis crop. As a result, it begins to compete for oxygen and said nutrients. It might not be taking much away, but it's still preventing your plant from reaching its prime.

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The problem gets dire, however, once the algae dies. At this stage, microscopic fungi will appear and begin decomposing the algae, attracting your crop's deadliest enemy: fungus gnats. These little menaces will chew countless holes through the roots of your plants, creating vulnerable points where pathogens can deal the final blow to your crop.

How To Manage Algae In Your Hydroponic System


So, now that you know the harm algae can cause when left unattended, you'll need to get rid of it fast. First, however, you'll need to learn how to identify it when it appears. From there, you'll need to not only focus on treatment, but take steps to prevent future algae growth as well.


Algae commonly appears as a green, fuzzy growth. However, the appearance of red, black, or brown varieties is far from unheard of. Searching for these physical markers is the simplest approach, but the menace can often hide in the shadows. To find it without visual indicators, all you have to do is take a good, long sniff. If you notice an overly mouldy and earthy scent permeating the room, you've likely got a case of algae on your hands. Lastly, pay close attention and note if your plant's leaves are yellowing and roots start clumping together. At this point, there's little that can be done—but treatment in the earlier stages can render this a non-issue.

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Speaking of treatment, a hydrogen peroxide cleanse is the most common approach when algae has already entered the system. Specifically, create a solution of one part hydrogen peroxide and ten parts water, then frequently mix small amounts of it into your reservoir. Along with getting rid of the algae, this even gives an oxygen boost to the roots! However, we only advise doing this with older plants, since young ones could get damaged even by a small amount of peroxide. After cleaning, make sure to replace any transparent growing components with opaque materials. If that’s not possible, find a way to make your existing tools opaque.


From there, we get into the issue of prevention, where there are quite a few options at hand. Since you can't get rid of the nutrients, warmth, and moisture, you'll have to focus on controlling light. This process starts when building your setup. As long as you prevent light from hitting wet areas, the reservoir, and other areas where water is stored, you should be clear of algae. Don't fear if you already have transparent equipment, though, as wrapping things up in aluminum foil should do the trick. Installing UVC lights in your air filtration system will also take care of any microorganisms before they even touch your system. Lastly, algae has never been a fan of moving water. Install a pump in your system to prevent the flow of water from going still.

Bottom Line — Protect Your Cannabis Plants From Algae


We hope this article helps you as you assemble and troubleshoot your hydroponic setup. Remember, algae won't present a major danger at first, but can do damage sooner than you'd think. Take steps to prevent it before anything, but if it occurs, you'll need to act fast. Be sure to check out our blog to learn more about the ins and outs of growing cannabis.


Written by: Ryan
Cannabis writer born in Southern California and based in Portland, Oregon. Follow AKA Carpenter on all streaming services.

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