So, a lot of people have said that the bacteria in a biological filter will die if you turn your filter of for too long (others disagree, or give time limits etc).

My question is, why would they die in that environment, when they don't die in the bottle the come in?

I'm guessing it's because (some) bacteria can just go into a kind of stasis in the absence of the right conditions, and just start respiring and growing again when good conditions return. Either that, or some bacteria can form resistant 'bacterial spore' bodies that 'sprout' again when good conditions return - likes seeds.

Any insights?

I don't think the filter bacteria are spore formers. The bacteria required in the filter are present in the environment and I wonder if the bacteria in the bottle is mainly food to encourage them to multiply. What the hell--I have never used them but if they work go for it.

I think it was The Skeptical Aquarist that has a good run down on them and if they work. If I remember correctly the conclusion was that the were spore forming (or go into a suspended state), and that they were nitrifying bacteria, just not the ones the will form develop time (to replace the ones from the bottle).

Edit, the above should have read:

...the conclusion was that they were spore forming (or go into a suspended state), and that they were nitrifying bacteria, just not the ones the will develop over time in the filter (to replace the ones from the bottle).

pretty much work as a back up bacteria untill the real good guys come in and do it properly.

I don't think the filter bacteria are spore formers. The bacteria required in the filter are present in the environment and I wonder if the bacteria in the bottle is mainly food to encourage them to multiply. What the hell--I have never used them but if they work go for it.

I think you're right, Alan - I did a bit of googling, and it would appear the bacteria in the starter products are a type of nitrifying bacteria, but not the type that establishes a cycle long-term. So they help with water quality initially, but I don't know if they accelerate establishing a "proper" culture of nitrifying bacteria :dunno:

I think you're right, Alan - I did a bit of googling, and it would appear the bacteria in the starter products are a type of nitrifying bacteria, but not the type that establishes a cycle long-term. So they help with water quality initially, but I don't know if they accelerate establishing a "proper" culture of nitrifying bacteria :dunno:

I'm sure that was what I meant to say, I blame the fact that the coffee hadn't kicked in and I was rushing to get out the door to start at 7.

my theory im working on atm (would love a couple of tanks to be able to experiment on) is that this means that adding the bottled bacteria every time you do a water change would actually be detrimental as it would compete directly with the REAL nitrifiers.