How often do you need to clean an aquarium filter? Before answering this question, it should first be clear when and why a filter needs to be cleaned regularly.

When does an aquarium filter need to be cleaned?

There are two methods to determine if the filter needs cleaning.

1. If the water flow or a surface movement (if set) is hardly or no longer present. This can be determined by moving the filter outlet over the water surface or by feeling it with a finger.
2. In the second method, the remaining flow is measured. To do this, take a standard measuring cup and use it to catch the water from the filter at the outlet for one minute. Then calculate the amount of water in the cup times 60 to get the volume in one hour. If this amount is less than 50% of the volume of the pool, the filter should be thoroughly cleaned.

Why does a filter need to be cleaned regularly?

• Clear water – if the filter hardly pumps any water, correspondingly fewer large or even small particles are filtered out of the water.
• Current/surface movement – some fish need a stronger current to feel comfortable or surface movement is needed to have enough oxygen in the aquarium.
• Pollutant degradation – due to the fact that less water flows through the filter, it takes longer for pollutants in the water to be degraded.

How often do you need to clean an aquarium filter?

This question cannot be answered unambiguously, as several factors such as filter size, fish stocking, planting and feeding play an important role. However, it can be assumed that an aquarium with a suitable external filter must be cleaned once or twice a year at the most. For a tank with a small internal filter and a high fish population, cleaning once a month may well be necessary.