Cloning Filters

[Egmel]

I've heard a lot of people talking about cloning filters recently and I sat down and had a think about it the other day. Surely if you introduce a new filter to an established tank and run it then it will take on some of the bacterial load of the tank. However the ultimate number of bacteria in the established tank will remain the same since they cannot outgrow the ammonia supply. Therefore when you remove the new filter to put it in the new clone tank you will remove a proportion of the bacteria from the established tank and cause it to go into a mini cycle with ammonia and nitrite levels above zero.

Now obviously the smaller the tank the more noticeable this will be but has anybody experienced this and if not can anybody explain to me why it doesn't happen?

TIA

 

[Jules H-T]

Theory: Because the bacteria are in constant competition with each other for resources, and are restricted by their availability. As soon as you remove some of the media, the remaining bacteria colonies up their ingestion rates and multiply, as a reaction to the relatively increased food/fuel. This deals with the increased bioload. The reaction is pretty prompt. Provided you don't take too much of the media out, you'll be OK.

Practice: I have a Fluval 2, Fluval 4, and Eheim 2027 running on my 70G. I can remove either of the Fluvals without noticing any blips, and the Fluval 4 is instantly able to take quite a high bioload in another tank without going into a cycle.

 

[Bignose]

The other thing is that, especially at the warm temperatures in our tanks, bacteria will take about 24 hours to double, given no resource limitations.

So, even if the cloned filter takes on 50% of the duty (probably nowhere near, especially since most of the bacteria are sessile, not mobile, and if the bacteria are being fed they are very unlikely to leave their perfectly good home), in 24 hours the original filter will have doubled its bacteria and will probably be sufficient to process all the ammonia once again. If you checked endlessly, there may be the slightest hint of mini-cycle for a few hours, but I have never read of anyone ever having problems cloning a tank in this way.

 

[Egmel]

Cheers for the responses guys, Sort of what I was expecting but worthwhile checking anyway