Water is a habitat not only for fish, but also for a lot of bacteria and plants. Similar to organisms on land, oxygen is necessary for them to survive. Fish and crustaceans have gills to absorb the oxygen for respiration. They need a minimum of 4 mg O2 per liter of H2O to survive without damage.
To avoid (or cure) that, it is possible to enrich the water with air. This is very advantageous for still waters like lakes or ponds, where no natural flow takes place. Here, the aerator produces some water flow to enrich the water with air (which consists of approx. 21 % of oxygen).
The model RX-2 consists of two wheels where in between are six baskets mounted. The baskets are open on top and have a lot of small holes at the walls and at the bottom. This ensures, that, when the wheels turn, the baskets are filled quickly when diving into the water and empty slowly in a lot of thin water jets, maximizing its efficiency by creating turbulence in the water.