Cycle Outside Of The Filter

[PascalKrypt]

Sorry for the confusing title -- I wasn't sure how else to condense it.

Basically what I would like to discuss is how much of the cycle do you estimate lives on the tank walls, decorations, plants, and in and on the substrate in a tank?
Let's say for arguments sake this is a well-stocked, well-planted tank with a filter just the right size for the tank.

Let's take this hypothetical for instance: if I were to take out the filter media of such a long-running, established tank, but leave the circulation pump on, what % of the stocking would the cycle remaining in the tank itself be able to support?
0%? 30%? Anywhere in between? More?

Has anyone ever tried it? I think I saw a thread many months ago were someone said they had turned off the filter on a tank of several years and they never saw a mini-cycle, but that seems a bit optimistic to me.

 

[maggie thecat]

Beneficial bacteria live on all of the tanks surfaces, but the ones in the filter media also get the water exchange. People do run filter less planted tanks, a web search should bring up loads of examples of people modeling their tanks on nature.

Back in the early days of aquarium keeping, it was fairly common.

 

[david1978]

Its possible. If you have either some flow in the substrate or enough plants. I ran guppy breeding tanks with just a boat load of guppy grass. My daughters tank is a 20 gallon with just a betta and a bunch of pest snails. I have a bubble bar in the gravel and no plants but its holding a cycle for over a year now. The only issue is you lose your mechanical filtration part of it.

 

[PascalKrypt]

Ah, maybe I should have made the original post more specific. I actually have a lot of experience running filterless tanks. But those were all established filterless.

What I'm wondering about is how to transition from a well-stocked tank on a classic mechanical filter to a filterless tank without having to start from scratch. How much of the stocking should I remove? I was thinking about the bare minimum (just put in one or two fish and build from there) but if anyone has tried it and concluded that say, 20-30% of the stocking is supported, that would be immensely helpful.

 

[maggie thecat]

How much mechanical filtration are you currently running on the tank? If it were me, rather than de-stocking, I would up the number of plants (top plant with pothos or some of the other popular nitrogen sponges and add other water plants) and reduce the amount of filter media over time.

 

[PascalKrypt]

How much mechanical filtration are you currently running on the tank? If it were me, rather than de-stocking, I would up the number of plants (top plant with pothos or some of the other popular nitrogen sponges and add other water plants) and reduce the amount of filter media over time.

Well, the reason for doing this is that I want to put the filter elsewhere. So removing the media bit by bit isn't really a great option though I will consider it (I do have an extra powerhead or two laying around). Filterless tanks are great and have a lot of advantages, but seeding them can be a bit of a challenge if you don't think to hang in an extra sponge filter well ahead of time

I guess I could consider seeding some extra plants from another established tank. Thanks for the idea!

I got this tank from someone else, it is rather a bit overstocked for my taste but since most of the stocking won't mix well with my other tanks I planned on moving the entire stocking + filter to a larger, new tank that I just got unexpectedly. But that would leave the original tank without a filter and I don't have an extra cycled filter to put in. So instead of restarting the tank from scratch I thought I would just add one or two fish that should be able to maintain whatever cycle is still inside the tank, pop in some new sponge filters and possible a powerhead and then gradually grow it out from there over the coming weeks. The problem is that I've never done it before with a tank that only contains inert matter aside from some clumps of plants and I have no idea how much of the cycle will remain after the filter is removed.
So I was looking for some estimates.

I don't actually know what kind of filter is in there as I've never seen it before and there doesn't appear to be info on it, but it produces quite a bit of flow for the size of the tank (sinking food getting blown about across the substrate despite the outflow being directed towards the surface from the middle of the tank) and it doesn't appear to have trouble supporting the overstocking in the few weeks I've now had it with normal water change schedule.
It is a 20 gallon stocked with 18 small and mid-size tetras plus a pair of balloon mollies (which works somehow). It is about medium well planted, with large clumps of fast-growing stem and floating plants.

 

[maggie thecat]

Huh. Well in that case, provide aeration , plant heavily and watch your water parameters. Also go ahead and drop in a sponge filter. Bacteria grow quickly. There were some charts or graphs on the exponential growth rates on the water subforum, I think on the topic of bacterial bloom.

If things start going sideways re establish hob filtration.

 

[PascalKrypt]

Huh. Well in that case, provide aeration , plant heavily and watch your water parameters. Also go ahead and drop in a sponge filter. Bacteria grow quickly. There were some charts or graphs on the exponential growth rates on the water subforum, I think on the topic of bacterial bloom.

If things start going sideways re establish hob filtration.

Do you happen to know where I could find that thread? I looked in the subforum but nothing stood out to me.
I didn't even know we had a nitrogen cycle subforum! Should have posted this there...

 

[maggie thecat]

Things have been re-arranged since the last time I looked (I've been off the forum for a while) but if you can seed a sponge filter in four weeks...

Thing is, the tank is cycled. Short of taking everything out and bleaching all the surfaces, that isn't going to change. You are going to lose some functional filtration, but it's not going to disappear entirely, you're just changing the filtration method.

You could add a glug of beneficial bacteria, to counterbalance the numbers you lose in addition to increasing the nitrogen absorbing plants.

 

[PascalKrypt]

Sooo thought (since I've seen some other threads about this in the meantime) that it may be of interesting for others if I updated this thread with my experience.

A few days after this topic, so about a month and a half ago, I removed the filter from this tank (20 gallon) and moved it to a new, uncycled, bare 50 gallon. Just over half the population of this tank was moved with it, and after two weeks of stability I moved in a new fish. The tank has been fully stable since that day, though I did a few extra large water changes with vacuuming in the first few days to ensure any remaining build-up would be taken care of.

To my knowledge, there has been no rise in ammonia or nitrite (at least not in the moments I measured it).
The original stock at the time of moving the filter was:
- 3 Panda Cories
- 4 Pristella Tetras
- 5 Glass Bloodfin Tetras
- 2 Balloon Mollies
- 3 Glowlight Tetras
- 5 Cardinal Tetras
- 1 Assassin Snail
- a hefty population of pond snails

What was left after the move: 3 Glowlight tetras, 5 Cardinal tetras, the Assassin snail and one Glass Bloodfin tetra I gave up on catching after 3 hours of trying. I was desperate not to disturb the plants too much as I was counting on them to help maintain the stable condition of the tank.
Tank contained six bunches of fast-growing plants. After the filter was moved, I added floating plants: pistia and duckweed. For the first few weeks, I also fed sparingly to help cut back on waste.
After two weeks, I added a half-grown male Apistogramma Cacatuoides.

The tank has been filterless since around the 10th of October. It has no tech in it now aside from the light, at first I was considering adding a bubbler or sponge filter but so far it has not proven necessary, fish respiration is normal and there are no problems with stress or disease. Interestingly, plant growth has exploded since removing the filter which had a pretty heavy flow. The balance in growth (as in, which plants grow the most) has shifted as well, probably due to going from strong flow -> no flow.
I will likely repurpose this tank for labyrinths and move the tetras to a tank with some surface agitation in due time, but nonetheless I am very surprised that an air stone is not proving necessary for them.
(Oh, and the assassin has seriously reduce the snail population, which has probably also contributed to a major waste cutdown).