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Comparing different types of aquarium water filtersFeatured science projectScience project video


This science fair project was conducted to compare the effectiveness of different water filtration systems used in aquariums. The experiment involved the under-gravel type filter and the sponge filter.


Sponge aquarium filters are more effective than under-gravel filters.

Scientific Terms

Filtration, ammonia, nitrite, nitrate, bacteria


Aquarium water filtration

All fish aquariums will require some kind of filtration system to maintain the quality of the water inside the fish tank. This is because the fishes continuously produce waste inside the water. The filter will help remove the dirt particles, ammonia and nitrites from the water. There are 3 common classes of filters for aquariums – biological, mechanical and chemical.

Biological filtration involves growing some useful bacteria in the filter. The bacteria will help to convert the ammonia in the water into nitrites, which is safer. Another group of bacteria will later convert the nitrites into nitrates, which are even less harmful. The ammonia in the water is produced by the fishes’ gills, urine and other decaying organic matter in the water.

Mechanical filtration helps to remove waste particles by pumping the water through a porous material or sponge. The dirt particles will get trapped in the filter. This filter will require regular cleaning and replacement of the sponge.

Chemical filtration involves passing the water through a carbon filter in order to remove the materials that are dissolved in the water. Odors, ammonia and some toxic metals can be removed by this process.

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Complexity level:
Project cost ($):
Time required:
1 day to prepare, 28 days for the science project experiment
Material availability:
Easily found
Safety concerns:

Basic safety requirements