Should aquarium filters run continuously?
Written by
Hoang Long
Reviewed by
Prof. David Walsh, Ph.D.Filters must be in constant use in aquariums to keep up safe water conditions. The colonies of bacteria present for cleaning can only survive in an uninterrupted flow of water that is kept moving to sustain them. Without that flow, they die within hours; their death causes the desire for ammonia to accumulate, and the fish are threatened immediately.
Biological filtration crashes quickly during power failures or when workmen forget to turn the system back on. Nitrifying bacteria are at work twenty-four hours a day; when the water stops moving, they are deprived of oxygen. I have never witnessed an ammonia level below 1.0 ppm a few hours after a filter is shut off; in fact, in one instance, the level doubled in four hours.
Biological Stability
- Nitrifying bacteria require constant water flow
- Oxygen deprivation kills colonies within 2-4 hours
- Ammonia conversion stops immediately without flow
Oxygenation
- Filter returns oxygenate water surface
- Stagnant water loses dissolved oxygen rapidly
- Fish gasp at surface within 6 hours of shutdown
Toxin Control
- Ammonia accumulates 0.5 ppm per hour without filtration
- Nitrite levels rise dangerously after 8 hours
- Chemical filtration stops adsorbing toxins
Nothing like a power failure to put us in a crunch! Battery backups can run for 8 to 12 hours, or you can try manually aerating the tank using air stones. Be sure to keep some ammonia-neutralizing chemicals around for emergencies. Have your water parameters checked after the power has been restored.
Keep your filters alive and well! Do not shut down completely for cleaning; clean the mechanical media in the tank during partial water changes. Save water by rinsing media in that water rather than in the waste pile. One excellent way to do this is to plumb in two filters. That way, while you are cleaning one, the other can continue operating.
Select trustworthy equipment that enables continuous operation. For example, canister filters with quick-disconnect valves enable maintenance to be performed without shutting down the system. Sponge filters run off air pumps that can have their own backup, like a battery. And, purchase quality powerheads that are built to run 24/7.
Never intentionally shut down aquarium filters, even while feeding. Fish continually produce waste, and therefore, waste should be processed continuously. By continuing to run a filter, fluctuations away from a safe parameter can be better controlled. Your aquatic ecosystem relies on biological filtration, which is dependent on consistent operation.
Read the full article: Understanding Aquarium Filtration Systems
