How Do You Stop and Get Rid of Algae Growing in Hydroponics?


The issue of algae is normal in aquaponic and hydroponic systems, albeit more potent in the former. Unless you neglect your systems and let them get out of control, algae growth actually won’t do much damage. Nonetheless, it can be pretty worrying and annoying for growers. 

Aquaponic algae

Although it is normal for algae to infiltrate into aquaponic systems, they are especially infuriating at the start. The worst, and unfortunately the most common algae that grow in aquaponics are green algae. This alga has chloroplast with both single- and multi-celled organisms. If you own anything with water, chances are you have seen green algae. 

Two major problems with algae

Algae can spoil pipes and ruin other physical aspects of aquaponics. That’s not the worst. Importantly, the two most severe issues that algae can cause are related to oxygen and pH levels. 

First off, algae forms oxygen via water molecules while taking in carbon dioxide for energy in the day. When it gets dark, this process is reversed. This leads to a dip in oxygen levels, which is the first way that algae ruin aquaponic systems. 

This changing oxygenation makes for a tedious measuring of dissolved oxygen as growers who take readings near evening time might not notice anything out of the norm yet suffer damaged crops. Growers would probably know of this only if they decide to take dissolved oxygen measurements in the wee hours. 

The second way that algae interfere with dissolved oxygen levels is by dying then rotting, causing the rapid depletion of dissolved oxygen. Although this is fine in aerobic settings, it can be detrimental in aquatic domains for the fishes, plants, and even bacteria.

To prevent this, growers should either remove dead algae before they build up or at least get more oxygen into the system through increased circulation.

The second major issue with algae is the diurnal pH swings that it causes due to its intake of acidic carbon dioxide in the day (pH rises) and release of the weak acid in the night (pH lowers). Thus, new growers might misattribute this pH swings to a failure in the system rather than those pesky algae. 

Prevention is better than cure. The following are some steps you can take to not only reduce algae growth but also prevent them from growing in the first place. 

How to tackle algae issues — Aquaponics

The basic measure that you should be taking regardless of your system’s “algae situation” is to ensure temperatures are just right for your plants and fishes and to check that phosphorous levels are not excessive. 

Thereafter, aquaponic systems that are still infested with algae should be treated with both shading and mechanical filtration, the two simplest ways of managing the algae. 

Shading is exactly what it means. You should shade your system or tanks with opaque covers — like a black piece of tarp — to starve the green algae of light, thereby inhibiting their growth. Alternatively, growers can paint their tank black followed by a layer of white paint. This not only prevents the temperature in the tank from rising, but it also stops algae build up. 

For algae that grew on the surface of your media, you can add rocks or gravel till they reach the water surface to shade the light.

The simplicity of shading might make it seem useless. But don’t be fooled as this is a highly effective and quick strategy for getting rid of those pesky algae.

Many farmers also use a mechanical filtration in their systems which contains technologies such as vortexes and filters, specially dedicated to eliminating algae from the water. It can be costly to purchase but you can always DIY one for less money. 

In fact, if your system has a grow bed, you already have a form of mechanical filter. You might not realize it but the grow beds actually act as filters that separate algae from your solution, which is pretty cool if you ask me.

Other than shading and mechanical filtration, there are plenty of alternative methods out there. You just need to search the internet for the one that suits your system best. That said, here is a trade secret that happens to be many farmers’ top strategy. This strategy entails adding humic acid to cloud the water, shading your tank. But a caveat is that it only works for deeper depths of solution. If your tank is too shallow, it can backfire as the acid will trigger algae growth. 

Even so, many farmers still use this technique as it has a host of other main benefits such as stimulating crop growth and improving their health by providing several crucial nutrients. In fact, the shading for deeper solutions is just an extra advantage.

This clean, simple, and affordable fix to many farmer’s algae issues makes it highly attractive and hence, deserving of its title as a trade secret.

At the end of the day, the ideal solution is a mixture of filtration, shading, and perseverance. The essence of any system is the forming of ecology. Algae blooms are vital, and even inevitable in these systems. They might be annoying at first but once they find the equilibrium in the system, they will no longer cause you and your crops severe issues. 

But before that happens, you need to take control measures and wait it out. Sometimes, the hardest thing anyone can do is wait. But trust me, your effort and patience will not go unrewarded. 

Hydroponics algae

The severity of algae blooms in hydroponics is secondary as they have fewer reasons to grow and if they do, the environment is too small for them to colonize. As a result, managing algae is much simpler for hydroponics. 

Like in aquaponics, the first method is shading. The second technique is the use of Ultraviolet (UV) clarifiers. These filters function by introducing UV light to the solution, disinfecting the medium of bacteria and algae. UV clarifiers are a great way to manage algae accumulation, boost crop health, and ensure hygiene in your hydroponics. 


As you can tell, algae problems in aquaponic systems are way more severe and harder to manage than those in hydroponics. But don’t let that faze you, especially if you’re a new grower, as there are plenty of measures available to you to prevent these issues from worsening. Furthermore, algae bloom rarely cause severe issues in the long run anyway. As long as you give your aquaponics or hydroponics systems the proper attention and patience to improve it, there should be no reason for algae problems to spiral out of hand. 


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