Internal filter changeover

[Ogertron3000]

I’m finally replacing my old internal filter. It’s served me well but it’s 15 years old and time to go.
I just purchased a nice modern slim corner mount one and put it in. I have left the old one in to help the seeding process, how long do you guys think hi I I need to leave them both in there before I get rid of the old one?
I thought about transferring the old media but it’s so old the sponge has pretty much disintegrated so I’m happy to wait for the new media to become biologically active.
Also since we have a long weekend next week I’m considering doing a whole strip down rescape so im guessing that would slow the process down a bit?

 

[esoxlucius]

I have a bit of a dilemma with situations like this. BB numbers will only increase if the bio load increases. So, if your bio load is the same then why would BB quickly start colonising your new filter when you've got ample numbers of happy established BB in the old one! It makes little sense, to me anyway.

Granted, you will no doubt get some BB in your new filter, eventually, but if I was in your shoes, to speed up the process, I'd take the media out of your old filter and shoehorn it into your new one, or squeeze and rinse the hell out of your old sponges into the tank water and let your new filter suck in and trap all that BB rich gunk (this way can look quite unsightly for a day or two until the water clears, but it's effective).

And of course reduce feeding for a couple of days, and if it gives you peace of mind you can test your parameters too just to ensure the transition is good.

 

[jjohnwm]

I have a bit of a dilemma with situations like this. BB numbers will only increase if the bio load increases. So, if your bio load is the same then why would BB quickly start colonising your new filter when you've got ample numbers of happy established BB in the old one! It makes little sense, to me anyway.

Granted, you will no doubt get some BB in your new filter, eventually, but if I was in your shoes, to speed up the process, I'd take the media out of your old filter and shoehorn it into your new one, or squeeze and rinse the hell out of your old sponges into the tank water and let your new filter suck in and trap all that BB rich gunk (this way can look quite unsightly for a day or two until the water clears, but it's effective).

And of course reduce feeding for a couple of days, and if it gives you peace of mind you can test your parameters too just to ensure the transition is good.

That's an interesting way to look at it. I always give a new filter at least a few weeks to mature before I think of removing the old one (or the new one, if I just want it to start up another tank). Certainly, this seems to work for me. When one of the filters is removed, it's often possible, with careful testing, to detect a slight blip in ammonia/nitrite levels, but it is very brief and minor since the generation time of the bactieria is so short that the correct population is restored very quickly.

I would think that the colony of bacteria...the population of which is, as you say, dependent upon available nutrients...is constantly experiencing a changeover as old bacteria die off and newer ones replace them. Since bacteria are reproducing by means of division, there aren't really old ones dieing of old age, but there must be some attrition as newer, healthier generations outcompete and replace older? They don't stop reproducing, but many fail to survive. This is supposed to be one of the benefits of a fluidized filter media; the tumbling action facilitates the removal of older, dead/dying bacteria to be replaced by stronger stock.

How do bacteria appear in a new unseeded tank? Whatever the mechanism, it is a longer, slower process than what occurs in a tank that is seeded with old media, or with "bacteria juice" squeezed from an old filter, but it happens. So if bacteria can appear unaided in a fresh set up, then moving from one filter to another within one tank is a simple matter.

In a tank with a constant unchanging bioload, there will be X-number of bacteria. If an additional biofilter is added, it will eventually be colonized, but then it and the old biofilter will each bear fewer bacteria, since the same constant bacterial population will be spread out over a larger area, i.e. the two filters as opposed to one.

Does this make sense? To me it seems to...but then, I am easily confused...

 

[esoxlucius]

I'm no microbiologist so I can't back my theory up with any any research painstakingly carried out in a lab or anything like that. But it just makes complete sense to me, though of course my theory is probably complete twaddle. Talking twaddle and getting confused goes hand in hand with the aging process, lol.

I just imagine it to be way quicker putting the old media in the new filter/squeezing sponges out into the tank than plonking the new filter in and waiting and waiting and waiting for the new filter to establish itself......especially when there hasn't even been an increase in bio load to kick-start the BB into multiplication mode.

Now of course if BB are materialistic creatures, and enjoy only the best things in life, then they could also swiftly move accommodation from their manky old filter into a nice new shiny one, though I don't think it works like that!

duanes , what's your take on this.

 

[tlindsey]

I agree with the above except wouldn't worry about squeezing out the old disintegrated sponge filter the bio bacteria are sessile.

 

[jjohnwm]

I agree with the above except wouldn't worry about squeezing out the old disintegrated sponge filter the bio bacteria are sessile.

Yes they are...and that wonderful brown pudding-style sludge you squeeze out is composed of gazillions of particles of decomposed organic waste, each coated in bacteria! Your new filter extracts them from the water column, and now you're golden. You've got a brand new filter already loaded with a bunch of hungry, maybe-slightly-confused bacteria, rarin' to go.

 

[duanes]

Should take 6 weeks for the new filter to be fully colonized, if just plunked in the tank, without any extra seeding.
But bacteria are opportunistic, so they will colonize whatever is there, more nutrient load or not
I always use some pieces of old media in a new filter, but....
what bio-media is in the old filter? is it just the sponge? or is their something more? it only takes a little.
And at this point, your entire tank is colonized, the substrate, the sides, rocks, wood, and plants, everything.
As long as it is not overly stocked, bacteria population should ramp up to meet demand.

As an example of its colonizing ability......
We used Chloramine as a disinfectant at the water facility where I was analyst, on a 5 to 1 ratio (5 parts chlorine, 1 part ammonia), my tap water would normally present an ammonia reading of 0.2ppm.
As an experiment we checked different points in the distribution system for ammonia consuming bacteria, it was found clinging to the surface of all pipes, in all areas, from close to the water plant, to the furthest ends of the system.

 

[Ogertron3000]

Thanks guys, very useful responses.
Your input has helped me come up with a plan, feedback would be appreciated.
The new filter is currently in the tank straight from the box, Sunday is normally the day I do a water change of approx 2/3 of the volume. Since I want to do the rescape next week I might skip the wc this week but tear some of the old sponge From the original filter and put it in the new one (the sponge is the only media in both filters)
2 days before the big rescape I will squeeze the crud out of the old filter into the water. Water clarity won’t be an issue as it will be nearly all changed a few days later. I’m hoping the old media in the new filter and 2 days to absorb what’s in the water will get the new filter colonised enough.
My concern is I will lose a lot of the good bacteria that’s in the tank during the rescape by scrubbing the glass and all the wood decor (black beard algae getting out of hand). At the same time I will be adding a fair bit more wood, rocks and plants.
The only fish are 2 blue acara at almost adult size and a 5 inch red tail shark that was an unwanted gift from the LFS. It’s a 40G tank so I’m not really going to add anything else anytime soon.
Hopefully even though it will be very disruptive to the whole tanks ecology it won’t cause a full crash or restart the whole cycle.

 

[jjohnwm]

That's more or less a variation of what I have done many times; never any problems. You might get a tiny snippet of ammonia, so fast and so little that you might miss it if you aren't checking for it. I usually feed very lightly or not at all for a couple days as a precaution.

It's really not that disruptive to the tank's biological processes, more visual than anything else.

 

[FJB]

One way to do it is to run both filters for a little while (couple of weeks?), then remove old filter but place all its media in bags and put them in the tank, and gradually remove portions of it until all gone. Another way is to swap old and new filters but use all media in new filter. There are other ways as well, they should work equally well.