Re: [APD] if power goes out, how long before bacteria die off?

["Phillip Grobler" <pfgrobler at hotmail_com>]

I do not know  the biology behind what I'm saying  and its purely based on
my understanding of the world.

It seems the bacteria will die quite quickly when there is a lack of oxygen.
The lack of food Ammonia
 or Nitrates are not that important in the short term. So when the power
fails the lack of O2 is the
most likely killer of the bacteria.

The actual size of the bacteria colony and the type of filter will greatly
influence how long they will last.

In  a heavily loaded system there will be a larger population of bacteria to
cope with the day to day
Ammonia reduction. And when the power fails it will use up all the available
Oxygen quite  quick.
So the bacteria will start to die much faster.

Canisters - will deplete the supply of oxygen fairly quickly. And there is
no way to replenish the
oxygen supply.

Internal box filters  and under gravel  filters should last slightly longer
since diffusion can take place
 to supply small amounts of O2 to the filter. They will also still provide
some filtration around
there edges while there is no power

External hang-on filters and trickle filters have an advantage that even
during with a power failure
the bacteria will have more than enough O2 available to them. So they should
survive quite easily
until the thin water layer dries up. It most cases this could take several
hours or even days. The
filter is useless while there is no power but the bacteria will survive
until the power is back.

Natural - Plants / live rock / plemium will keep on working regardless of
the power failure and is
perhaps the safest of all. Especially in marine setups that use live rock or
plemiums, where the filter is
all natural, part of the display and not powered by pumps.

So filter performance during a power failure from worst to best is:

Fluidized sand
Canister
Internal Box
Under Gravel
External hang-on
Trickle
Natural - Plants / live rock / plemium

This is all based on the assumption that the bacteria die due to a lack of
oxygen.

I have had a tank using a trickle filter with out power for more that a day
with no. Ammonia spikes afterwards.
The ammonia spiked during the power outage but recover quite quickly when
the power was restored.

Phillip Grobler
Cell: +27 083 654 0250
Instant messaging:
MSN: pfgrobler at hotmail_com
Yahoo: pfgrobler at yahoo_co.uk
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