Last Updated on July 20, 2021 by Marco C.
What is an airstone? It is an important part of any aquaponics system as they provide much-needed aeration to the water efficiently. Air Stones come in different shapes and sizes depending on your need and how to efficiently aerate your water. This article will be discussing how air stones work when to use them, and how to clean air stones.
What Is An Airstone?
An airstone is a solid object dotted with micropores connected to an air pump. They sink down the water to ensure that the deepest part of the water receives proper aeration. Air stones require an air pump to deliver air. Air stones are commonly used in aquariums and even hydroponics units to ensure enough dissolved oxygen is in the water.
The Micropores In Airstones Create Smaller Bubbles, Which Increase The Surface Area Of Contact Between Water and Air
By pumping air through micropores, airstones create smaller bubbles in the water. This increases the surface area of water being aerated. Big bubbles compared to small bubbles with the same amount of air passing through have less oxygen exchange. The equation for the surface area of a sphere can be defined as:
A = 4 π r2
Wherein r = radius of the sphere
Having small air bubbles mean less radius, but as the saying goes, the sum is greater than the whole. Let us take for example 1mL of air as big bubbles compared to 1mL of air as small bubbles. Volume will give us the radius of one bubble compared to 1000 small bubbles from the equation:
V = 4/3 π r3
Given 1mL of air as a constant, a big bubble will have a radius of 0.62cm and a surface area of 4.836cm2. If we have a similar 1mL of air as 1000 small bubbles, this will give us a radius of 0.062cm with a surface area of 0.04836cm2 per bubble. Multiplying the surface area of the small bubbles by 1000, this will give us a total surface area of 48.36cm2. This is an increase in surface area of 10 times from comparing one bubble to 1000 small bubbles. Increasing the amount of small bubbles through micropores give us more surface area for the same volume of air being pumped.
What Are The Benefits Of Having Micropores In Your Airstone?
Oxygen exchange between water and air happens through the surface of bubbles. With more bubbles, you are effectively increasing the surface area of contact where oxygen exchange occurs. Oxygen dissolves in your water which is needed for plant roots as well as fish. According to Dr. Lennard, the aeration that happens mostly comes from the bubbles breaking the surface of the water allowing atmosphere to mix in with the water as well. Oxygen also dissolves in water through the sprinkling of water through the air and back into your system like a fountain or a waterfall. Airstones also stir the water to ensure a uniform distribution of nutrients and dissolved oxygen among different components.
How Many Airstones Should Be Used In Aquaponics?
Dissolved oxygen allows fish, plants, and bacteria to respire and continue biological processes. Nutrients and chemical processes also consume oxygen in transforming chemicals to useful nutrients. Fish need dissolved oxygen to breathe through their gills. On the other hand, plants need dissolved oxygen for respiration through roots and leaves. Bacteria also use oxygen in nitrogen fixation since the conversion of nitrogen between forms is an energy-intensive process.
It Is Important To Aerate Your Water As Much As Possible, Adding Multiple Airstones Per Component Will Increase Yield and Health Of Your System.
You can not over aerate your system since most of the oxygen will always be used or evaporate into the atmosphere. A general rule of thumb is to ensure that each component that utilizes dissolved oxygen should have its own airstone. The main components that need airstones are the hydroponics unit, the fish tank, and the biofilter.
To ensure that each component has enough dissolved oxygen for organic activities, it is important to measure concentration. Measure dissolved oxygen by using electric dissolved oxygen meters or by titration. If no means of measurement are readily available, fish and plants have natural indicators of low dissolved oxygen levels. If fish stay close to the surface, it is a sign that the fish tank does not have enough oxygen. Root rot occurs as well when there is not enough dissolved oxygen in the water for your hydroponics unit.
Read more about: How To Make A Venturi Water Pump For Aquaponics
Airstone Maintenance and How To Clean Air Stones
As air stones stay submerged in nutrient-rich water, the micropores get clogged by biological material or sediments. If not much buildup has occurred, it is possible to just put them in clean and fresh water and have the air naturally push out the biological material. To ensure this, I personally wash the air stones regularly at least once a week by letting them run in clean water.
If it has been covered in algae and sediments, it might require strong acid to remove the proteins and precipitate. It is possible to use muriatic acid to unclog the micropores. When handling muriatic acid, ensure your own safety by wearing googles and rubber gloves. Avoid using your hands when dealing with muriatic acid as well. Leave the air stones in undiluted muriatic acid for an hour before removing using tongs. After which, leave the air stone out for a day to dry. Leave the air stone in freshwater for a day to ensure that the leftover acid is removed before returning back into your aquaponics system. This could unclog most of the micropores and increase the number of bubbles coming from your air stone like it’s brand new.
Air stones are an essential part of any aquaponics system. The benefits and uses of air stones are overlooked and used for aquariums and fish tanks, it assists with the biological activities of plants and bacteria as well. Micropores and smaller air bubbles are what make air stones special, although make-shift systems of pipes drilled with small holes work as well.