# Is it possible to cycle a small tank?



## sparkyjoe (Feb 27, 2012)

OK, I've been reading a LOT of info on this forum as well as doing other research and I'm confused about the ability to cycle a tank under 5 gallons.

From what I understand, the ability of a tank to hold a stable cycle is directly dependent upon the amount of surface area in that tank on things like the substrate, decor and the filter. And from what I understand, the vast majority of the BB colonize in the filter.

So... A smaller tank may have less general surface area in the way of tank walls, substrate and decor, but if it has something like a sponge filter in it, and those are known for the amount of surface area they contain for the growth of BB, then wouldn't they be able to allow a smaller tank to establish and hold a stable cycle? 

I honestly want to know 'cause I've been pondering this question for weeks.

I've got mostly 5 gallon tanks myself, and I prefer cycled tanks, but I'm running out of room and a 3-4 gallon tank might fit better in some places but I don't want to have to deal with multiple water changes each week.


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## Mo (Mar 15, 2012)

Supposedly yes, a small tak can cycle. Bt becaus elf how unstable the water parameters will be. The cycle will be very difficult to establish and keep healthy


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## wystearya (Sep 27, 2010)

One idea might be to get a sponge filter rated for a larger tank. It would take up more room, but it would be a good place to grow the beneficial bacteria.

Maybe you could try it and just see if it works? I assume you have a water test kit to keep track of the ammonia/nitrite/nitrate levels.


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## sparkyjoe (Feb 27, 2012)

Yeah, I have a test kit.

I don't know that I'd want to try it with my betta boys, but I just got some cherry shrimps and thought of building them their own little deluxe home some day.


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## Mo (Mar 15, 2012)

Maybe try it out with guppy fry?


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## sparkyjoe (Feb 27, 2012)

Mo said:


> Maybe try it out with guppy fry?


Yeah, maybe... would Endler's work? Maybe just a fancy male guppy. I've been wondering about one of those too.

Hummmm, something to think about.


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## Mo (Mar 15, 2012)

I would try endlers as they are hardier due to the minimal amount of inbreeding, compared to guppies


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## sparkyjoe (Feb 27, 2012)

Yeah, that and I think they're smaller so less bio-load.

Fortunately I have someone in the area that raises Endler's as well as Fancy Guppies so I can get them without paying for shipping and probably at a slight discount.


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## Mo (Mar 15, 2012)

Good to know! I would love to see the results! Everybody can definitely benefit from this experiment too.


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## LittleBettaFish (Oct 2, 2010)

I think small tanks can hold a cycle if you use a filter with a high capacity for biological filtration. You need a disproportionate amount of beneficial bacteria to deal with the faster spikes of ammonia and nitrites.

This is why nano tanks with surprisingly high stocking levels also use canisters. Not only does it provide good circulation, but it also provides an enormous amount of surface area for BB to colonise.

I think utilising live plants is also key to stabilising a cycle in a small tank. They will help deal with excess nutrients in the water column and generally prevent any sudden spikes from occurring. 

I think it would be harder maintaining anything under 2 gallons as it is just such a small body of water but 3-4 gallons should be able to manage it.


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## sparkyjoe (Feb 27, 2012)

Yeah, that sounds about right. I have one of my boys in a cruddy little 3.5 gallon and I'd like to upgrade him and move that tank to another area of the house. I've wanted to experiment with sponge filters, so maybe I'll have to try it once I can afford to upgrade my boy.


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## Thunderloon (Feb 6, 2011)

I'm not going to bother to read the posts above.

What it comes down to is simple... FLOW is only for stirring the tank water in large tanks, it has nothing to do with filtration effectiveness.

As a general rule of thumb you need one cubic inch of colonized biological media per gallon of tank. Think of it as fish-per-fish. It takes a fish one second to produce as much material as the inch of low density foam reduces to nitrate.

You could go out and buy some cheap children's blocks to get the little inch square by two inch tall single-post blocks then bore a hole through the top to fit in about 7 inches of 3/8 inch diameter pipe and then shove an inch square by inch and half tall chunk of medium density foam up inside. You then use air-hose and a pump to jet air bubbles into the top so they flow up the 3/8ths pipe. This DIY filter will handle a single male Betta day-in-day-out without problem and will maintain its own cycle indefinitely once it is established.

The whole selling point for mass-market filtration is that they can move more water quicker over a small filter to filter larger and larger tanks with the same small HOB system. But honestly filters such as small Tetra and ALL Aqueon systems are useless for biological filtration if left unmodified.

Lets look at what the bacterium need:
_ Darkness
Water flow
Something to grow on
A way to propagate around
Food
Calcium and trace minerals 
Oxygen 
Temps from 67°F to 83°F_

If all those are present then you could cycle a single bio-ball inside a piece of tubing.

What you have to understand is that more than 103% of the rumors about what doesn't work in cycling are spread by the people who don't even understand the basics. 

Lets look at a Walstad!
http://theaquariumwiki.com/Walstad_method

I have some issues with this article... not sure where and who decided that Dr W. endorsed potting soil made mostly of compost which always contains decayed animal and plant matter. Just assume that the correct way to Walstad is to go get a shovel of nice dirt and adjust it with dirt from other locations to get the right soil mixture. Buying a bag of soil is the worst way to start one.

So in the Walstad the plants are the pump and the soil is the mechanical and biological media. Additionally the plants can directly absorb some of the ammonia and nitrite in the water but the predominance of these chemicals is actually slowly pulled down into the soil by the root flow cycle the plants generate. While in the soil these chemicals are consumed by the bacteria and the result is nitrate. A solid rule of thumb for any Walstad arrangement is to never have dirt deeper than the roots of the plants you wish to use. Dirt below that depth is just a harborage for anaerobic and cyanotic bacteria.

The soil bed in a Walstad is the buffering system for the health of the tank... Walstads are not simply NPT. Walstads are tanks ballanced specifically to ONLY need replacement of water, feeding of their population and the replacement of fish that die or become too large for the arrangement. You can have Walstad as small as one liter in size with 1/3 of that volume used in the soil bed.

So a Walstad has about ten cubic inches of filtration per fish due to the speed that the filter cycles. We're talking only a few milliliters per day per inch of fish with the rest of the biological processing relying on diffusion and transpiration.


Opposite of a Walstad is a marine nano-tank. A tank that relies both on filtration capacity AND natural filtration by "live rock" and live coral.
This kind of tank is a little odd to freshwater/tropical enthusiasts because the primary life form in the tank isn't actually a fish or a plant but is a porous material in which the bacteria inhabit the bio-media out in the open in the tank as well as in the rear in some combination of submerged and wet-dry filtration. These tanks are designed for the most hard-core of aquarium fools: "people with way too much money". To set up the cycle in these tanks you have to follow a tight set of parameters for water, heat, light, flow and fish load as well as calculate in how much biological load your coral will add AND remove from the system. These numbers are actually different depending on whether you're going to keep plant eaters, flesh eaters or a combination of both and only the most accomplished aquarium keepers can maintain them year after year without resets and break-downs of the entire tank. Hardness has to be precisely regulated in these tanks and due to the salt water there are almost ZERO planting options, so extraneous solutions such as protein skimmers and phosphate reactors are often needed if you wish to keep the consumption of replacement water to a minimum. The bacteria involved are also slightly different. In a general sense you cannot skimp on biological processing surface area in these tanks. They tend to have 5 or 6 inches of filtration running at high flow rates per inch of fish. A good example is the Fluval Spec nano tank. The filtration system uses a 3"x8"x1.5" foam block with an inserted carbonate nodule bag and the minimum flow on the pump is too high for most freshwater fish to be comfortable. The sea is all about rapid mixing and flow of water. The delicacy of operating these tanks is intense and yet I've seen a two liter fully cycled nano-tank using just a circulation pump and coral/live rock.

In all three of these examples the biological processing occurs in a submerged porous material with water flowing through it. It doesn't occur on the glass or magically based on the water volume of the tank.

Last example: 
http://en.wikipedia.org/wiki/Georgia_Aquarium
http://www.youtube.com/watch?v=fjsfwqM8IJM
http://www.georgiaaquarium.org/newsroom/pressKitFiles/LIFE_SUPPORT_SYSTEMS.pdf

For those of you who don't like to side-read. 10 million gallons being serviced by 300,000 gallon per minute filtration. Roughly equivalent to 3gpm in a 100 gallon tank. In order for that to be possible the filtration must be single-pass complete. I can fairly well guarantee that the plants, coral and live rock do a lot of work but if you could imagine keeping a 100g marine tank but only having a whisper i5 filter as a primary filtration backup to your live rock you'll understand that it isn't the size of the tank that matters to the cycle, its the effectiveness of the filter.

You can cycle a Lee's sponge filter in a one liter bottle and keep a fish alive just fine. It isn't the water parameters or the feeding time that are at issue, it is the control over nitrate buildup and the water temperature that make maintaining a small tank difficult.

So when you look at anything written by anybody about how "small tanks can't be cycled" remember that the person is half right but all wrong.
We DON'T cycle tanks, we cycle filters.


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## sparkyjoe (Feb 27, 2012)

So TL, I think you're saying "yes" it can be done with a decent little sponge filter?

I love science but my brain isn't what it used to be so I'm gonna have to read your post several more times to get all of what you said.


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## Cattitude (Apr 19, 2012)

sparkyjoe said:


> So TL, I think you're saying "yes" it can be done with a decent little sponge filter?
> 
> I love science but my brain isn't what it used to be so I'm gonna have to read your post several more times to get all of what you said.


+1 "Oww. My brain" - Moleman of The Simpsons. 

Seriously, thanks for that post, it was actually pretty informative. I'm working on getting an empty 2-gal tank cycled right now as a temporary home for a betta I'm expecting next week. Once betta is upgraded to a larger abode I'll prob put a few guppies or neons in the smaller tank. In the meantime I will reread your post and links and see about adding some sponge somewhere as an extra bacterial growth medium.


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## sparkyjoe (Feb 27, 2012)

Cat, what are you currently using as your filter? I'm just curious.


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## Cattitude (Apr 19, 2012)

sparkyjoe said:


> Cat, what are you currently using as your filter? I'm just curious.


My tank is a few years old, it's a "marineland eclipse explorer" 2 gal with its own power filter. The media is a Z cartridge containing charcoal, a plastic screen and floss. The filter also contains a "bio-wheel" (which I've heard doesn't harbour beneficial bacteria as advertised). That said, the wheel turned a brownish colour when I was using the tank to keep a goldfish.

The intake is a tube which runs to the bottom of the tank just above the gravel. At the bottom of the tube there's a little "cage". I'm thinking of getting some loose filter floss and stuffing it loosely in the cage and lower part of the tube, to provide more media for bacteria to grow without clogging the filtration. Other option may be to toss the wheel if it doesn't work as a bacterial medium, and fill the wheel chamber with floss as well.


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## sparkyjoe (Feb 27, 2012)

I was considering the 3 gallon model. I understand the biowheel to be fairly good?

I've added a sponge to one of my uptake in one of my tanks. It's mostly to protect the shrimps, but I would think it would also act as a space for BB.


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## Cattitude (Apr 19, 2012)

sparkyjoe said:


> I was considering the 3 gallon model. I understand the biowheel to be fairly good?


I don't know for sure, but I never had any problems with the biowheel. It seemed fine for goldfish, which are pretty dirty. 

Now that I know to buy a water testing kit I will have a better idea of how effective this filter is. I'm just graduating from the "you can keep them in a wineglass with a few stones and a lucky bamboo plant" school of betta husbandry. :shock:


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## sparkyjoe (Feb 27, 2012)

Ha! Yeah, it's funny how many of us started with small, unfiltered containers & then upgraded.


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## Cattitude (Apr 19, 2012)

sparkyjoe said:


> Ha! Yeah, it's funny how many of us started with small, unfiltered containers & then upgraded.


I've got 4 of these empty, looking for new tenants. They're way too small for my tarantulas as well - too small even to culture feeder insects. And they're still selling them new at pet stores.


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## Hallyx (Jun 11, 2011)

As I have no substrate for my 5g, I compensated by putting about 4 cu/in additional foam around my filter (in the filter bay of my divided tank) in addition to the closed-ended foam tube on my filter outflow.

Thanks for all the tips and info, Thunderloon. 

I'll darken the filter bay. 

How do I get more oxygen into my system? I'm using a Hagen Elite Mini cartridge filter.


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## glitchsniffer (May 8, 2012)

This does make alot of sense Thunder. So by that thinking, if I were to say have a Tetra Whisper ex 40 for a 2.5 gal tank it would be more likely to hold a cycle? Not to mention that it would be too much for a betta but for example only. Being that the filter would have more surface area to hold bacteria? Not saying I have that filter but is that the jist of the thought. If so I may be willing to try that and see what happens. Fish out cycle that is. Petco is running a sale right now on the Aqueon 2.5g mini bow and I just purchased one. I really didn't have any plan for it but for 25 bucks I really couldn't resist. This might be a fun experiment. I do have another 2.5g mini bow with a betta in it, and a 6.6g bookshelf that I am currently waiting to cycle. I was also thinking of coupling the two tanks to make them easier to cycle. Via either some sort of piping between the two with a filter sucking out of one and depositing into the second. The only problem with that would be consistent heating. I do wonder if that would be possible. Maybe a cannister filter across 3 or 4 minibows. Makes another intersting idea for another experiment. Fishless again of course!


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## Ilikebutterflies (May 19, 2012)

I have this same little tank (the Eclipse Explorer 2g w/biowheel). I have since upgraded to a 10g for my new little pet but was debating on returning him the the Eclipse when my new pair get here so they can live in the divided 10g. The bio wheel filter worked really well for my 55g that I had several years ago so I thought it would be fine. Then I read that one cannot hope to cycle such a filter for a small tank like ours.
I personally think the teeny bit of carbon is useless and was debating just leaving an old cartridge in and rinsing it out every so often if gets clogged in order to keep a place for the bacteria to grow besides the bio wheel. I thought about just replacing the cartridge with a sponge too. The cartridge is 2.75x4 which yields 11 square inches. The biowheel appears to offer an additional 2 inches of surface area. I was considering making a sponge cover for the inlet to slow the current down a bit which would add even more surface area. BTW I found that keeping the water level slightly higher than the bottom of the return chute greatly reduces the turbulance created by the returning water.
So, in theory, that should be MORE than sufficient to clean up after 1 betta. I think the only way to cycle this small of a filter would be to do it fishless for a few weeks because wouldn't doing partial water changes make it impossible for the filter to ever properly cycle?


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## Cattitude (Apr 19, 2012)

Ilikebutterflies said:


> I think the only way to cycle this small of a filter would be to do it fishless for a few weeks because wouldn't doing partial water changes make it impossible for the filter to ever properly cycle?


I have read other posts that say it's impossible to cycle a tank that's less than 5 gal. That said, I test the water in my explorer 2g tank every couple of days (liquid, not strips) and I've yet to see an ammonia spike in 2 months. I just left the filter and bio-wheel as is with no modifications, but I do 50% water changes twice a week. I just have one male betta in the tank. 

Water changes, especially partial ones, don't affect establishing a cycle. The beneficial bacteria mainly cling to surfaces. The filter media (and bio-wheel) provide a lot of surface area. Changing the media is what is most detrimental to cycling. Just rinse it out in old tank water and don't change it every month as the cartridge instructions tell you.


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## Hallyx (Jun 11, 2011)

glitchsniffer said:


> ... I was also thinking of coupling the two tanks to make them easier to cycle. Via either some sort of piping between the two with a filter sucking out of one and depositing into the second....


I _messed_ (the operative term here) around with a filter in a separate 1/2gal feeding into two small show tanks, siphoning back into the 1/2g. Apparently siphoning works a lot better when the water levels are really disparate. When the tanks are close to the same depth even a large tube does not reliably siphon. That's what the "mess" reference is about. 

I finally got my homemade bubbler built and my spare 2.5 g cleaned. I start cycling tomorrow. I'll post my results on a new thread. I encourage you to do likewise.


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## sparkyjoe (Feb 27, 2012)

Looking forward to the results, Hallyx.
_Posted via Mobile Device_


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