Do filters eliminate water changes?
Written by
Susan Taylor
Reviewed by
Prof. David Walsh, Ph.D.Aquarium filtration systems do not negate the absolute necessity for water changes. While ammonia and nitrites are processed, these toxins are not removed by filters due to the presence and gradual increase of nitrate solutions. This physical dilution is necessary for eliminating these toxins. They also supply important minerals to the solution, such as calcium, which are not restored by the filtration system.
Nitrate Management
- Filters convert ammonia to nitrites then nitrates
- Nitrates accumulate beyond 20-40 ppm becoming toxic
- Only water changes physically remove nitrate buildup
- Test weekly with liquid test kits to monitor levels
Mineral Replenishment
- Fish absorb calcium and magnesium from water
- Filters don't add these essential minerals back
- Regular water changes restore depleted trace elements
- Use remineralized RO water for sensitive species
Organic Waste Removal
- Fish waste and uneaten food bypass mechanical filtration
- These decompose into harmful dissolved organic compounds
- Siphoning during water changes removes settled debris
- Prevents algae blooms and bacterial imbalances
Carry out water changes systematically to achieve the best results. Always match the temperature of the water you add to the aquarium to avoid shock. Always treat tap water with a dechlorinator. I vacuum the substrate when removing the water to remove debris from the aquarium system. This two-step method enables stable parameters to be maintained, allowing the tank to be cleaned effectively.
Weekly monitoring of your water parameters is crucial. Test for nitrates weekly using liquid test kits. Test for pH and hardness monthly. All of these tests will indicate how frequently you should perform water changes. My planted tank requires changes every two weeks, while my cichlid tank requires water changes weekly.
Combining filtration with disciplined water changes is optimal. Filters handle your biological processing, while water changes address what the filters cannot handle. This together produces the healthiest environment for your aquatic life. Reliable maintenance keeps problems from occurring before they become detrimental to your fish.
Read the full article: Aquarium Filter Types: Your Essential Guide
