In an aquarium, phosphate primarily enters the water as a result of the digestive processes of the fish or in the form of food remains. In ponds, phosphate primarily enters the water as a result of leaves and dying pond plants/algae. If conditions are unfavourable, the phosphate levels may reach values that are sometimes 100 times higher, and more, than natural levels. Undesirable algae will then multiply exponentially as an inevitable consequence.
Recommended phosphate values:
Freshwater aquarium (community aquarium): 0-0.4 mg/l
Lake Malawi/Lake Tanganyika aquarium: 0-0.4 mg/l
Plant aquarium with few fish (aquascaping): 0.1-1.5 mg/l
Marine aquarium: 0-0.1 mg/l
Pond: <0.05 mg/l