Selecting a filter can indeed be a confusing task for beginners. Before choosing a filter, it is essential to understand what filtration is. Recently, the most frequent question I have received is: How should one select a filter? Next, I will use simple and understandable language to explain in detail the principle of filtration and how to choose a filter suitable for one’s own aquarium.
The Role of Filters
Filters effectively remove impurities of various sizes from the water, including fish waste, fish food residue, substrate sand, dust from volcanic rock, and some metabolic products from fish bodies, as well as decaying aquatic plant leaves. When water flows through the filter media layer, nitrifying bacteria begin to act, breaking down the highly toxic ammonia nitrogen and nitrite in these impurities and converting them into less toxic nitrate. These terms may be unfamiliar to you, and I will explain them in detail in later articles. You only need to understand that the death of fish in the aquarium is closely related to these factors.
The Cycling of Filtration Process
The filtered water contains tiny particulate impurities and a small amount of harmful substances, which then re-enter the secondary cycle. Repeatedly, theoretically, the water obtained in the end is almost free of impurities, and the content of ammonia nitrogen and nitrite in the water is very low. However, the concentration of less toxic nitrate will gradually increase, and if the nitrate concentration exceeds the standard, it can also harm fish. This is why even aquariums that have been filtered still need regular water changes.
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