Question On Changing A Filter

[P&J]

To preface, I've searched a bit and found a ton of threads about changing filters, but I haven't found the answer to this sub-question:

If I change my filter, I understand that I should run the old one for a while to let the bacteria migrate. But once I let the bacteria migrate, won't it be a half and half distribution? So no matter how long I run both simultaneously, won't I be 50% short on my bacteria and run into a mini-cycle when I take the old one out?

-P

 

[Tolak]

Depends on the filters & stocking. In most cases such as these the new filter is an upgrade, with more media. A mature colony of nitrifying bacteria is capable of doubling in 24 hours.

Sometimes capable is not always real world. To help with this, fast the fish for at least 24 hours before removing the old filter, and feed lightly for the next week, less food equals less waste produced.

 

[petertr]

To preface, I've searched a bit and found a ton of threads about changing filters, but I haven't found the answer to this sub-question:

If I change my filter, I understand that I should run the old one for a while to let the bacteria migrate. But once I let the bacteria migrate, won't it be a half and half distribution? So no matter how long I run both simultaneously, won't I be 50% short on my bacteria and run into a mini-cycle when I take the old one out?

-P

Its a very good point, and one that I made in a couple of recent threads.

The answer I was given was that you can routinely remove 1/3 of your biomedia when cleaning a filter, as the colony can double in size in 24 hours.

Soi having a 50% filter is going to be fine withing 2 days. Perhaps a 33% water change after 12-24hrs to make sure.

 

[P&J]

Thanks for the quick advice!

-P