Colonizing new filter media

So, I'm starting a new tank, and I was planning on using old filter media. The only issue is, my old filter, in a 5 gallon, has only a sponge in it, and removing all filter media from the old tank seems like a bad idea idea, since I'm planning on keeping that tank running.

My idea is to add new filter media to the old filter solely for the purposes of transferring the bacteria from the 5 gallon to my new tank. I was wondering how long it will take for the bacteria to colonize the new filter media sufficiently for this to work. Anyone know?

Edit: Also, what is the best filter media for this purpose?

 

You've got it! Removing the old media from the established tank won't do any favours for the "donor" filter.

It usually takes a few weeks to properly colonize the new media—a month is ideal, if you've got the time. If you're in a rush, any time spent in your filter is better than no time with extra media, but you'll need to proceed with caution if it isn't seasoned for very long. You can also speed up the process by moving some substrate, decor, or driftwood from the old tank to the new one.

I prefer medium-coarse sponge for my filter media, but bio rings, fine filter floss, or pretty much anything else would do the trick. Good luck!

 

I think I've got a plan. It only just occurred to me, lol. I've purchased some bioballs. I'll plop as many as possible into the old filter, and then transfer one or two into the new tank in about a week to see if they help with the ammonia levels. Then, a few days later, I'll transfer a few more. I'll repeat this process until it appears to be having an effect on my ammonia levels. Then I'll have my answer for how fast new media in an old filter gets colonized.
Yay science.

 

Also, your new tank will only be "seasoned" for the same amount of bioload, or possibly less than what was living for beneficial bacteria from the doner tank... In that 5 gallon tank, the beneficial bacteria colonies will only grow to size needed for the bio load in your 5-gallon tank to eat the amount of ammonia and nitrite produced in that tank.. it will not hold/grow beneficial bacteria in reserve so to speak. I hope this makes sense and that it did not confuse you.
But it will certainly help kickstart your beneficial bacteria colonies when you are starting your cycle in the larger tank

 

Also, your new tank will only be "seasoned" for the same amount of bioload, or possibly less than what was living for beneficial bacteria from the doner tank... In that 5 gallon tank, the beneficial bacteria colonies will only grow to size needed for the bio load in your 5-gallon tank to eat the amount of ammonia and nitrite produced in that tank.. it will not hold/grow beneficial bacteria in reserve so to speak.

I am aware, lol. Microbiology is kind of a hobby of mine. I figure that, even if the population isn't large enough to completely clean my tank, it will affect the ammonia levels in some fashion.
You know, another thing I could try is cutting a bit of the sponge from the donor tank off...

 

or you could just squeeze the current filter foam into the new filter box... you just require the bacteria, not the physical sponge...getting the beneficial bacteria colonies actually started is the trick here...once started they establish themselves. Some people dose to 2PPM or even more, depending how many fish they initially want to add when the cycle completes, I however think it best to add fish very slowly when starting to stock a tank...adding too many at once will certainly create an ammonia spike

 

I'm actually only keeping invertebrates in this tank. My plan is to stock 10 different species of invertebrate and then let them multiply, so maybe my starting plan needs to be different than the standard fishless cycle.
I think what I'll do is add the invertebrates first with the new filter media, wait a couple of days for them to produce enough ammonia to feed a population of bb, and then add the bit of old sponge to seed the new filter media.
Or squeeze the old sponge into the new filter. Whatever.