Seeding A New Tank

[TrickySpot]

Hi Guys,
 
I recently got a small tank just for propagating plants, and put a few zebra danios in to provide some ammonia to get the cycling going. I intended to immediately replace the filter's sponge with a piece of sponge from one of my larger tank's filters, but waited a day or two. Ammonia was at 2 ppm (2 mg/l) when I did the sponge change, but the ammonia doesn't seem to be dropping and its two days later. How long does a 'cycled' filter take to remove 2 ppm of ammonia?? 
 
Thanks!

 

[the_lock_man]

It depends upon how much bacteria is on the piece of sponge that you have moved - it may be that you have moved a sponge with no A-bacs on it, but all N-bacs, so you would just see a nitrate reading rise, but never any nitrite. There is no way that I am aware of to predict where in a filter the bacteria types are living.

 

[TwoTankAmin]

t_l_m, the bacteria all live in close proximity to each other in a bio-film. If you move any bacteria you move both kinds and in pretty much a proper balance because you are moving the bio-film. There are also other bacteria living in the bio-film, including heterotrophs. There is even research showing where in a biofilms different bacteria live, how all the different types of bacteria work as a community.
 
So, while you hit the nail on the head regarding the possibility that there was not a lot of bacteria in the piece of media that was moved, if any nitrifiers were moved, it was both kinds as well as an assortment of other non-nitrifying bacteria.
 
The other things we can learn from all of this is  first, that when one moves media from a cycled filter to use in another tank, we really can not be certain how much bacteria we might be moving. Second, since people routinely move over roughly 25% of the bio-media and do not often have huge issues in the donor tank and then often see a slower start that expected in the new tank, a bunch of the bacteria must be living elsewhere in an aquarium. This is usually the substrate (or other hard surfaces).

 

[TrickySpot]

After 4 days the ammonia and nitrites were both 0, so at least in my experience you can cycle a tank with fish within 4 days if your recipient tank receives a 100% sponge replacement from a seeded tank.  

 

[TwoTankAmin]

Lets be clear about something, you did not "cycle" a tank with fish, you cycled it by moving in enough bacteria to do the job rapidly. You would have gotten the same result with no fish by adding 2 ppm of ammonia. In fact it might have gone faster using ammonia instead of fish as the fish took a while to make enough ammonia to get the bacteria to close the gap by reproducing.
 
I routinely set up a tank and fully stock it by using plants and media taken from other tanks. There is never an ammonia nor a nitrite reading in these tanks. But there was no cycling involved. they were 100% ready to go upon set-up.
 
But the last piece of this puzzle is what was pointed out above- there is no way to know how much bacteria one is moving.By any chance did you test the tank out of which you took the sponge? Did it have a mini-spike?

 

[TrickySpot]

Lets be clear about something, you did not "cycle" a tank with fish, you cycled it by moving in enough bacteria to do the job rapidly. You would have gotten the same result with no fish by adding 2 ppm of ammonia. In fact it might have gone faster using ammonia instead of fish as the fish took a while to make enough ammonia to get the bacteria to close the gap by reproducing.
 
I routinely set up a tank and fully stock it by using plants and media taken from other tanks. There is never an ammonia nor a nitrite reading in these tanks. But there was no cycling involved. they were 100% ready to go upon set-up.
 
But the last piece of this puzzle is what was pointed out above- there is no way to know how much bacteria one is moving.By any chance did you test the tank out of which you took the sponge? Did it have a mini-spike?

 
You are just arguing silly semantics now. Cycling a tank is the act of getting the nitrogen cycle running efficiently enough to have 0 ammonia, 0 nitrites and tolerable nitrates, which is exactly what I did. How you get there is up to you.

The doner tank is always at 4ppm, its drip fed with ammonia to cycle multiple filters at once. If you read my initial post properly, you'll see I said the filter is already cycled, or pre-cycled if you want to be picky!