Upgrading Filter

[DrSlackBladder]

My 100 litre has been running well for over two years now.  It has a mix of fish, but I'm planning an Amazon rescape and a switch to a decent shoal of cardinal tetras.  I want to do it gradually as nature takes its course with the current tank mates, so adding just half a dozen to start, then more over the coming months.years.  So a long term project.  Starting out preparing now with the rescape/replant, and upgrading the filter from the current internal Aquael Fan 2 (150 litres) to an Aquael Fan 3 (250 litres).  The filter sponge is of course bigger in the Fan 3 (therefore not interchangeable) , so I intend to run the new bigger filter in the tank either with the Fan 2, or maybe run the Fan 3 alone but place the matured filter sponge from the Fan 2 in the tank, hoping for migration of bacteria.  But I guess there's no reason for the bacteria to multiply or grow in the new sponge.....thought maybe I could gradually remove the old sponge filter by cutting a piece off every week, over a month or so, to force new bacteria to grow in the new sponge.  Are there any better ideas for conditioning the new sponge in the Fan 3?  Thanks.

 

[simplyfish]

Could you take the opportunity to switch to an external filter. I held off doing it for a long time, but now feel the filtration is better, quieter and less visible in my tank.
 
Other than that when you switch over, if you put the whole old sponge into then new filter then you should be able to switch straight over. You are moving the whole colony of bacteria in one go that way.

 

[DrSlackBladder]

Thanks for the reply.  But the old sponge is too small for the new filter, which I why I thought I could run the new filter and sponge but with the old colonised sponge in the tank, gradually reducing the size of the old sponge to force gradual colonisation of the new sponge, without danger of a spike.

 

[simplyfish]

You could perhaps cut a shape the size of the old sponge out of the new one and slot it straight in there...

 

[DrSlackBladder]

You could perhaps cut a shape the size of the old sponge out of the new one and slot it straight in there...

But then I'd have two that don't fit the new filter!!!

 

[simplyfish]

If you put them together, you'll have one...

 

[dave840f1]

Tyne valley aquatics have a product that mature your filter quickly, they are small balls that you put in filter and they desolve and seed your filter. You can get them on eBay. I would like to say at this point I have no interests in this company other than being a customer?

 

[DrSlackBladder]

Thanks.  I don't need seed material though, I have a fully matured filter sponge which has been in the tank for years.  Just need to get that colony into the new filter with a larger sponge/capacity.  Think I'll run the new filter and just place the old filter sponge in the tank for a month or so, checking ammonia and nitrite every couple of days, then eventually remove the old filter a quarter at a time, again testing water all the way.