THE BENEFITS OF AIR STONE
The simple truth is that an air-stone can be beneficial on a small scale. Bubble aeration is a good tool if you couple that with your other aeration devices. In the event that we suffer a power outage or possibly forget to turn our systems back on after a water change.. An air-stone could be the difference between life and death.
How many of us use battery operated air pumps when transporting fish? That small amount of surface agitation is enough to keep the fish's life supported in travel.
When you aquarium water temperature is higher, your evapouration rate will also be higher. With your tank's water evapourating faster, you will also lose more oxygen. If this is the case you may want to add an air-stone as an extra source of aeration.
Air stones can assist in moving the water which will benefit your filters. The air flow of an air-stone can be regulated to give you more or less aeration depending on your needs for any particular tank and of course providing the air pump has that capability. Although the amount of water movement is very low and would only be beneficial in small tanks.
Rufus my rope fish and Humphrey's my FlowerHorn both enjoy playing in bubbles. I assume they both find it entertaining in some way. In the larger tanks I personally don't find they add much aeration but the fish do like swimming through the bubbles.
There are other benefits that air stones provide. Biological filtration depend on the aerobic beneficial bacteria to breakdown nitrogenous waste in your aquarium. In order for this to occur there must be a steady source of fresh oxygen. Without the oxygen required harmful gases and chemicals can quickly build up creating a toxic environment for your fish. Bacteria need large amounts of oxygen to successfully do their job but if the supply isn't adequate, your fish may find themselves in an oxygen poor environment.
Often it's not realized how important good oxygen in an aquarium is to the inhabitants. Luckily there are ways to replenish and maintain a healthy environment by simply adding an air pump and air-stone. This will assist your beneficial bacteria in biologically filtrating your water without the depletion of oxygen that your fish need to breath.
The simplicity of an air-stone also will promote proper gas exchange by drawing the harmful gases that are accumulating at the substrate level like carbon dioxide. The bubbles help in transporting the harmful gases up to the surface, where they are then released into the atmosphere so they can't harm your fish. This process helps to stabilize your PH levels directly counter acting the harmful effects of PH- lowering carbon dioxide in your aquarium.
There are many forms of air-stones. There are discs, stones, bubble wands and air curtains just to name a few. Using your creativity you can construct and lovely display of soothing beneficial bubbles to your aquarium.
In closing there are benefits to using air-stones but they seem to be more pronounced in the smaller tanks. Excellent for transporting fish and in emergency situations. It's always good to have a couple around just in case. However, large tanks that need excessive amounts of oxygen, wouldn't really be beneficial other than the fish may find them enjoyable the play in.