Air Stones Don’t Starve Your Roots

By Shannon McKee
Published: February 6, 2017 | Last updated: March 25, 2019 06:19:03
Key Takeaways

Growing plants hydroponically is different from growing plants in the dirt, and one thing that some growers don’t think about is how to get oxygen to the roots of the plant. One inexpensive solution is to utilize air stones, which produce hundreds of tiny bubbles to increase the oxygen levels getting to your roots. Shannon Mckee explains the basics of air stones and why they are often necessary in hydroponic systems.

When growing in the dirt, you don’t have to consider how to get oxygen to your roots. That’s not always the case in your hydroponic system, and you may be neglecting this need. You may find that your nutrient solution provides dissolved oxygen to the roots, but what do you do if your nutrient solution doesn’t offer this or if the oxygen gets depleted? Air stones can help you oxygenate your system.


What are Air Stones?


If you’ve ever had a small fish tank, you might be familiar with air stones. These little balls connected to a line that connected to an air pump to oxygenate the water of your tank. Air stones for your hydroponic system are very similar. You can find a wide variety of pump and air stone sizes to fit your particular system. Like in the fish tank, each air stone will produce hundreds of tiny bubbles that will boost the oxygen levels in the water for your roots. Another benefit of using air stones rather than other options, such as ozone treatments, is that they are a relatively inexpensive fix to your oxygen issue.

What Happens Without Oxygen?


Without oxygen, the plants in your hydroponic system may not be growing to their full potential. Plant roots need oxygen for aerobic respiration, which gives the plant energy for the roots to grow and to bring in nutrients. A lack of this oxygen means that roots will be stunted and there will be a decrease in the amount of minerals and water that can be absorbed by the plants, which will, in turn, result in a lack of growth for the plant. This will signal your plants to produce ethylene, which is a stress hormone and can result in the plant being susceptible to pathogens.


Why Use an Air Stone?

An air stone is a good choice because of the small expenditure, the amount of oxygen it can produce for your system, and the ease of using it. Still, you may think, “Why not just use some tubing and an air pump, as that will get the oxygen into the water just as well without having to deal with one more part?”

Air stones are useful because of the way they produce oxygen. An air stone creates a huge number of tiny bubbles in comparison to the slower stream of larger bubbles that just a tube alone would create. Together, the tiny bubbles have a greater surface area that can help the oxygen diffuse better into the nutrient solution. This occurs because of the porous nature of the air stone.

Air stones also come in different sizes. You can buy long, thin ones up to a foot long for your rectangular tanks, or you can buy smaller oval, cylindrical, or round ones. Your system will determine the best option for you, and since they are relatively inexpensive, you can try several set-ups before you find the one that works the best for you.

It’s also good for the air stones to be lower in the water as the bubbles take longer to get to the surface. This gives the oxygen more time to diffuse into the nutrient solutions, giving better rates of dissolved oxygen.

Temperature and Oxygen

It’s important to keep in mind the temperature of the air that is pumped through the air stones in your hydroponic set-up. A colder system will be able to retain more dissolved oxygen than a warmer one. You may stress the plant roots if they are subjected to higher temperatures.

Typically, you want to have the temperature of your system lower than the ambient air temperature. As such, pumping warm air in your oxygenation system isn’t a good idea as it will increase the nutrient temperature. So, try to place your air pump away from lamps or other equipment that could warm the air you’ll end up using through your air stones.

Nutrients and Oxygen

With adding oxygen using air stones, you may notice that your nutrients are being depleted quicker than they were before adding this oxygen. This is because your plants are better able to absorb the nutrients in your solution. It can be a good idea to start testing the amount of nutrients more often until you find a rhythm of what your plants need now.

At the end of the day, whether you decide to use air stones, rely on the dissolved oxygen from your nutrients, or use some other method, it’s vital that you make a change and get more oxygen to your plants’ roots.

There are a few things that you’ll need to keep in mind when increasing the levels of oxygen in your hydroponic system, such as the temperature and the level of nutrients. In exchange for your hard work in keeping your plants’ roots happy, you’ll find that they will reward you with lush growth and better yields.


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Written by Shannon McKee | Freelance Writer, Gardener

Profile Picture of Shannon McKee

Shannon McKee lives in Ohio and has been a freelance writer for several years now, including on her blog, Nicknamed by loved ones a garden hoarder over the past few years, she grows a wide variety of plants in her urban garden.

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