painful news: one of the best fish keeper loss his fish pond this morning due to such…

Ideal aquarium ecology reproduces the balance found in nature in the closed system of an aquarium. In practice, it is virtually impossible to maintain a perfect balance. As an example, a balanced predator-prey relationship is nearly impossible to maintain in even the largest aquaria. Typically, an aquarium keeper must actively maintain balance in the small ecosystems that aquaria provide. Basic aquarium maintenance should generally be performed weekly to maintain optimum conditions for fish and plants.^[8]

Balance is facilitated by larger volumes of water which dilute the effects of a systemic shock. For example, the death of the only fish in a 10-litre (2.2 imp gal; 2.6 US gal) tank causes dramatic changes in the system, while the death of that same fish in a 400-litre (88 imp gal; 110 US gal) tank that holds many fish may create only a minor imbalance. For this reason, hobbyists often favor larger tanks whenever possible, as they require less intensive attention. This same concept extends to the filtration system as well, external (outside of the tank) systems in particular. Generally speaking, the larger the filtration system depending on its configuration, the more capable it will be of properly maintaining an aquatic environment. External filtration systems provide the added benefit of increasing the overall volume of water and its dilution effect. For example, a 190-litre (42 imp gal; 50 US gal) aquarium with an external filter that holds 40 litres (8.8 imp gal; 11 US gal) creates a 230-litre (51 imp gal; 61 US gal) aquatic system, an increase of over twenty percent.

A variety of nutrient cycles is important in the aquarium. Dissolved oxygen enters at the surface water-air interface through agitation or what would be observed as waves in a natural environment, and carbon dioxide escapes into the air. The phosphate cycle is an important, although often overlooked, nutrient cycle. Sulfur, iron, and micronutrients enter the system as food and exit as waste. Appropriate handling of the nitrogen cycle, along with a balanced food supply and consideration of biological loading, is usually enough to keep these nutrient cycles in adequate equilibrium.