Dick wrote:
I have air bubblers in all my tanks. Never gave a thought to them as
backup to the filters. One more reason to have air in the tank.

Actually, air bubblers have a minimal impact on oxygen concentration in
the water. It's surface water turbulence that provides enough gas
exchange. Bubbles are too small and their contact time is too short to
provide efficient transfer between phases.
If your filters go out, I'd recommend a power head producing water
surface movement.

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Victor Martinez
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