The Complete Guide to Algae Management in Soilless Growing

Another month, another newsletter, and today, we’re addressing a common concern for hydroponic and aquaponic growers alike: algae. While often misunderstood, algae can play a significant role in your system’s health and overall productivity. Let’s explore what algae actually means for your set-up and how you can manage it effectively. 

First, you must understand what algae is and how it develops in the first place. 

Algae, particularly green algae, is a natural part of growing in most aquaponic and hydroponic environments. This isn’t surprising, considering​​ algae thrive in the same conditions ideal for any other plant. To thrive, algae need lots of light, nutrients and lots of water.

While a small amount of algae in your system is normal and can even be healthy, excessive growth can lead to complications, so it’s best to get it under control. 

Algae comes in many varieties, including red, brown, and black. However, the most common form is green algae. When left unchecked, green algae will compete with your plants for nutrients, clog your plumbing, and even begin to impact water quality. 

Let’s address these concerns in more detail. 

Nutrient competition is a major concern when it comes to excessive algae growth because as algae multiplies, it takes up the nutrients intended for plants. This can lead to deficiencies in your crop, impacting growth rates, yield size, and overall plant health. In severe cases, your plants may begin to show signs of nutrient stress, including yellowing foliage or stunted growth. 

Another concern brought on by algae overgrowth is the depletion of oxygen in your reservoir. Algae consume oxygen and produce carbon dioxide overnight (just like any other plant would). The problem is that when algae growth becomes excessive, this process can drastically reduce the dissolved oxygen level in a grower’s reservoir. Not only does this reduce a plant’s ability to uptake nutrients, but it also stresses its root system and renders it more susceptible to pests and diseases. 

If those reasons weren’t enough, algae can also lead to pH fluctuations, which, while less obvious, can be just as detrimental to plant health. As algae photosynthesises, the pH of your reservoir fluctuates. These fluctuations can lead to nutrient lockout, where certain nutrients become unusable to plants despite their presence in the water. Over time, this instability can stress out your plants and reduce the productivity of your system. 

Finally, excess algae can clog system components like tubing and plumbing. Clogging is a practical concern more than anything else and can affect the efficiency of your entire setup. As algae grow and die, they can accumulate in pumps, filters, and pipes, restricting water flow and creating ‘dead zones’ where water cannot circulate. 

With these problems in mind, regular cleaning and maintenance become crucial in keeping your system healthy and algae build-ups at bay. The good news is that there are a ton of ways you can prevent and even treat algae once you notice it. This means algae is rarely life threatening to your crop. 

Light control is one of the more effective ways to prevent algae growth. We suggest using opaque materials when building out your system, especially in areas where water is exposed to light, such as reservoirs, pipes, and plumbing. Of course, it’s important that you provide ample light for your plants, but strategically blocking some light from water can go a long way in controlling algae growth. 

Naturally, regular maintenance is another non-negotiable if you want to control algae in your system. This means you must sanitise both the system components and the tools and equipment used within your setup—think scissors, buckets, sponges, and even your own hands.  

In addition to these passive methods of control, you may also consider implementing some more active methods of control. 

Beneficial bacteria can be a great natural solution, or, for something more acute, you may consider adding a diluted solution of hydrogen peroxide. If you do decide to add hydrogen peroxide to your system, do so with caution, as too much of a good thing can definitely harm your plants. Dosage rates vary, so always follow the application instructions on the back of the package.

If your system is facing significant algae growth, these preventative measures aren’t going to be much help. The only solution is a thorough cleaning of your system. 

Start by prepping a cleaning solution of hypochlorous acid and water, again, following the dosage rates listed on the back of the bottle. Before you begin the cleaning process, make sure to turn off and unplug your system and all its various electrical components. 

Next, remove the plants, drain the system of water, and remove all growing media. To prevent stress throughout the cleaning process, you may place plants in a temporary nutrient solution. Once empty, it’s time to disassemble your system, separating parts for easy, thorough cleaning. 

Begin by rinsing each component using a strong hose to remove loose algae before gently scrubbing your system with the cleaning solution you prepared earlier. 

After your system has been scrubbed down well, give each component a final rinse with clean, filtered water before reassembling. 

It’s important to remember that while algae management is essential, it is a normal part of hydroponic and aquaponics growing and, in small amounts, poses no threat to your system. 

If you have any questions about managing algae growth, call 1800 640 222 or visit us in-store for more information. We’d like to thank you once again for reading this month’s newsletter and as always, happy growing!