certain gasses can become trapped under the sand (i'm assuming you have sand) and if it's not dispelled regularly and then suddenly released it consumes the oxygen and the fish suffocate. By adding an airstone you guarantee oxygen for the fish...the only other thing you can do is add an annoying HOB filter that tricles into the tank and creates oxygen that way.
I personally never vaccum my sandbed...the plants are so numerous and the trumpet snails are everywhere so I don't do anything for it. Just the normal water changes and even those are few and far between because it is a heavily planted tank.
|