Beneficial Bacteria......

[Shaddex]

I have a Fluval 204 Filter that is cycled and been running for about 6 months.
I need to remove my fish from my 2ft tank due to setting it up as a full time breeding tank.
Question is, how long can I leave the filter without any fish in the tank?
I will leave it turned on but as there will be no fish waste, wont the bacteria die off ?

 

[Harlequins]

With no fish in there,why don't you add ammonia to keep it ticking over...

 

[TwoTankAmin]

No they wont die off. Here is how the person responsible for discovering which are the actual bacteria that we need in our tanks are has said about this issue:

For humans, the opposite of live is dead. So if a human being is not living they are dead. But bacteria are not human and have a third option which is a state of not living (meaning their metabolism is almost shut-off) but they are not dead. There are a few different terms for bacteria in this state but the most common term is “viable but nonculturable”. As stated earlier, in this state the metabolic activity of the bacteria is basically nonexistent and the bacteria can last a very long time in this condition waiting until conditions get better. This is one reason bacteria have been able to survive so long – they can shutdown and wait out bad environmental conditions.

One also reads a lot that since nitrifying bacteria don’t form spores (which is true) they cannot shutdown and go into a resting phase which is false. Nitrifying bacteria have a different way of maintaining their viability when conditions are poor which relates to the fact that they prefer to be attached to surfaces where they can develop a coating or shield of exoploymer substances (EPS) that protects them.

How long it takes dormant bacteria to recover depends on how long they have been dormant. However, if you want your bacteria to stay "awake" and thriving, just use low dosing of ammonia in the tank to keep them well fed. The equivalent to about 2 mg/l (2 ppm) should do the trick. Don't overdose ammonia as levels of 5 mg/l of ammonia or nitrite are fatal for these bacteria.