How long to keep an old filter on a new tank?

[Jen]

I just set up my new tank on Saturday, and I had to move my fish in pretty much right away. How long do I need to keep my old filter running to ensure that the bacteria starts colonizing in my new filter?

 

[StarOrbs]

When I switched my 55 gallon from my Emperor 400 to the Eheim 2026 I let the emperor stay 2 weeks just to make sure. Some say a week some say more.

 

[dream250578]

When I had to switch tanks (the old one broke) I had to swap everything over straight away aswell. I couldn't have my old filter running as my old tank was an all in one. I just took out my old filter media and placed this in a string bag inside the tank, I left it in for about 2-3 weeks and everything turned out fine. So 2-3 weeks should be fine I would say.

 

[Bloo]

OK, now here's a question then :
what if you leave both filters running in one tank for say 2-3 weeks.
Then take the one out to use in the new tank.
Will that not in effect halve the filtering bacteria of the old tank in one go and cause some nasty spikes....

 

[scott67892002]

thats what i plan to do when i get my new tank so would also be interested in answer!!

 

[basia]

I recently set up an external filter on my tank. I put the filter media from the old filter into the new filter along with new media because the external filter is bigger. So far so good.

 

[Jen]

I went from a hang on back to a canister... there wasnt any room to put the media in there, or that's what I would have done.

 

[Bloo]

OK, now here's a question then :
what if you leave both filters running in one tank for say 2-3 weeks.
Then take the one out to use in the new tank.
Will that not in effect halve the filtering bacteria of the old tank in one go and cause some nasty spikes....

I would still love to know if anyone has any input on this ?

 

[StarOrbs]

It may halve the bacteria but I've never had a problem with a nasty spike after I take the old one off. Also, appearently nobody else has had this problem either.

 

[pjfish]

I got a new bigger filter and ran both the old and new filters on my tank for about 3 weeks. Then I moved the old filter to a new smaller tank. Everything else in the new tank was new. Both tanks seemed to be ok and I didn't see any spikes.