Air Pumps/Bubblers

While air pumps are often used in aquariums, it’s important to note that they do not directly add oxygen to the water. What they do provide is water movement and surface agitation, which can enhance oxygen diffusion by increasing the surface area for gas exchange. However, air pumps are not strictly necessary for maintaining oxygen levels in your tank, especially if you have a filter that already creates water movement.

Why Don’t Bubbles Add Oxygen?

The reason bubbles don't significantly contribute to oxygen levels in the water is simple: bubbles contain air. As a bubble rises to the surface, the gas inside it escapes into the atmosphere. While bubbles may facilitate some oxygen exchange due to their increased surface area, the process is limited. Essentially, the oxygen in the bubble only has a brief moment to diffuse into the water before it escapes.

To illustrate this, think of how oxygen is transported within the human body. Blood cells use hemoglobin, an iron-protein complex, to carry oxygen through the body. If oxygen were to leave the blood, much like the gas in a bubble, the body would struggle to transport oxygen effectively — leading to serious health problems like the bends, which affects deep-sea divers.

The principles in an aquarium are similar. While bubbles may provide surface agitation and water movement, they do not contribute to oxygen saturation. The water's ability to hold oxygen is influenced more by factors like temperature, water surface area, and movement — not by the air bubbles themselves.

If you already have a Hang-On-Back (HOB) filter, an air pump may be redundant. In many cases, the movement created by your filter is sufficient for gas exchange. If you’re curious about how gases like oxygen behave in a liquid, delving into concepts like vapor pressure and partial pressure can offer a deeper understanding of this fascinating process.