How fast does a FX5 become toxic without power?

[HarleyK]

Howdy,

Best info I can come up with:

[SIZE=-1]The concentration of O2 in water required to support aerobic aquatic life is about 4 mg/dm"3[/SIZE]

(Elements of Physical Chemistry By Peter Atkins, Julio de Paula)

The time to failure of your beneficial bacteria and onset of anaerobic decomposition depends on how long it takes for oxygen levels to drop below the threshold. That in turn depends on factors such as

• oxygen levels in your tank at time of power outage - generally 8-14 mg/L (in turn depend on aeration, temperature, fish, plants,...)
• bioload in your filter (the more material for bacteria to decompose, the faster they use up the oxygen trapped in your canister, also related to:
• colony size of aerobic (beneficial) bacteria, the heavier populated, the faster oxygen is used

Bottom line: A new or freshly cleaned filter will not pose a hazard during power outage. An aged filter can go toxic quickly, as fast as 1.5h, as blackghostuk decribed above.

You can buy some time with --> THIS <--
It's a life insurance for your fish.

HarleyK

 

[blackghostuk]

Bottom line: A new or freshly cleaned filter will not pose a hazard during power outage. An aged filter can go toxic quickly, as fast as 1.5h, as blackghostuk decribed above.

The filter I lost in 1.5 hours was a mature filter with siporax and it was off a heavily stocked tank, so it will have had a lot of bacteria in it, and might have needed a clean - I cant remember.

I suppose it depends, as you say, on the amount of bacteria, the oxygen level, the starting ammonia level, time without power, amount of muck/cleanliness in filter, size of filter.

It's also another good reason to have more than one filter on a tank, as they will share the load, and therefore 'share' the bacteria. And a pretty good argument for a sump !!