Freshwater Equipment

Aquarium equipment keeps the water clean, warm and well oxygenated and gives plants enough light. A filter pushes water through sponges and ceramics where beneficial bacteria live and turn fish waste into less harmful compounds. A heater's thermostat switches heating on and off as needed and keeps the temperature steady even when the room cools down.

In a planted tank it is worth adding a CO2 system and stronger lighting: plants grow faster and algae find it harder to compete. An air pump helps when there are many fish or little water movement. A reverse osmosis unit suits species that need soft water and marine aquariums.

A common mistake is choosing a filter and heater that only just cover the tank volume. A little spare capacity makes the system more stable. Spare parts such as filter sponges, impellers and seals are best bought before the old ones wear out.