# Can a tank without a filter cycle?



## Hikari (Jul 12, 2011)

I've always thought that a tank needed a filter to cycle, but I've read online that it cycles even without one. When I set up my 5 gallon without a filter, is there anything special I have to do for a while until the tank "cycles"? Once I get my fish in the new tank, I plan on doing 100% water changes a week with maybe a little freshening up the water in between.


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## Oldfishlady (Mar 1, 2010)

The nitrifying bacteria for the nitrogen cycle need an oxygen source to colonize as well as surface area and food.....without a filter of some sort it will be difficult to establish a stable nitrogen cycle, however, lots of live active growing plants also will provide some oxygen-but generally not enough-but the plants themselves will function as filtration-provided that you have enough of the right species and not overstocked....

In a 5gal unfiltered tank-without live plants and a single Betta-you will not establish a nitrogen cycle, however, the Betta will be fine....water changes....I would recommend 1-50% weekly and 1-100% monthly to maintain water quality-provided that you don't overfed and uneaten food is removed within a reasonable time.....

Look forward to pics.....


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## Hikari (Jul 12, 2011)

Thanks. I actually have been looking for some plants to put in his tank, but can't seem to find any around here (I live in a very small town which doesn't have much of anything). I'm going to look for some in the city hopefully next week.

But even without the plants I would only have to do 50% changes a week? I always thought with an unfiltered tank you have to do 100% water changes weekly. Right now with a 2.5 gallon I'm changing the water 3 times a week, 1 100%, 1 50%, and 1 20%. Is that too much?


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## SnowySurface (Apr 25, 2011)

The only way I've heard of a tank cycling without a filter is with the use of live plants. Live plants can act as ammonia sponges and take the place of a filter in the cycle. The annoying part is that not every plant available absorbs ammonia well enough to cycle a tank and the tank has to be very densely planted for it to work. I can see someone cycling a tank with plants so a betta with very large fins can be in a cycled tank without dealing with strong current. I only have a betta classic (the tail type that just dangles) and a crown tail, so I didn't have to worry about current as much. 

However, a tank full of stagnant water and fake plants wouldn't cycle on its own. You would have to have an ammonia source to jump start the cycle and then time for the nitrITEs to produce nitrATE growth. The decore and the walls of a tank will hold onto beneficial bacteria but I think the growth would be a little on the slow side. It took me 4 1/2 and 6 weeks for my two 5 gallon tanks. So, a tank without a filter may take 7 weeks (as a guess; I'm far from an expert).

Since your tank wouldn't have a filter to hold on to bacteria, I don't think you should do 100% water changes. Everytime you rinse the entire tank, you lose all your bacteria off of the walls and any decore. That would crash your cycle and make you start over again from scratch. I would do something like 25% twice a week and 50% once a week with gravel vacuuming. That way the walls never get dried out completely, the decore is also left alone, but the water is refreashed often and waste is removed from the tank. 

If my advice does suck (which it may XD), a last ditch attempt at cycle tracking and water changing schedules I like to use it the constant water testing method. It is as simple as testing your water so often you feel like you want to chuck your liquid test out a window. If your levels are good, you are doing it right. If your levels are bad, then you are doing something wrong. If your test are always good, then you cycled your tank well and you are changing the water on time. The time it takes to cycle and the tank's water change schdule may not match forum suggestions, but it works for case by case tanks. 

I hope this helps. Cycling a tank can be annoying and there is no one way to do it. I personally like using filters to cycle my tanks because they make cleaning and maintainance so much easier for me. Good luck.


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## Oldfishlady (Mar 1, 2010)

In a 5gal unfiltered tank with a single Betta-your not going to establish the nitrogen cycle-the bacteria need oxygen-but due to the volume of the tank-vs-stocking-you should be able to maintain water quality with 1-50% weekly and 1-100% monthly....provided that you don't overfeed and uneaten food is removed within a reasonable time

In a smaller volume of water...2.5gal unfiltered-twice weekly is needed to maintain water quality....1-50% and 1-100%......even with a filter in a 2.5gal twice weekly is needed..1-50% water only and 1-50% to include substrate cleaning by vacuum or stir and dip method....


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## ANHEL123 (Jul 21, 2010)

All my bettas have 2.5 gall each. I do 100% water changes every 4 days. But i also make sure no food go to the bottom of the tank ever. My oldest betta about approximetelly 3.5 years old. I live may be a cup of the original water. I don't have filters.

Sorry i put my post at the same time with Oldfish lady,but i didn't know before how to change them and someone recommended to me 100% so that is what i do since i have them.


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## Hikari (Jul 12, 2011)

My betta has really long fins, so I think he would hate any kind of current. I really wouldn't want to wait that long for the tank to cycle, though. If I were to put some food in until I put him in the tank, would it still help start the cycle?

I'm glad I've been doing the water changes right with the 2.5 gallon.  I just do an extra 20% change the day before the 100% just to freshen up the surface of the water a little, and I actually only started adding that recently. For over a year he's been fine with the 1 100% and 1 50% weekly.

I'm really anxious to get him into the 5 gallon now since I won't have to change his water nearly as frequently! I have to wait for another 2 weeks or so because we're getting new windows in the kitchen, and I need to be able to take him to another room when they are being installed since it will be very noisy. I would never be able to carry the filled up 5 gallon down the hall, at least not without seriously shaking up my fish! So when I finally can put him in the 5 gallon, can I just plop him right in with 100% clean water, or should I add some of his old tank water in with him?


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## Hikari (Jul 12, 2011)

ANHEL123 said:


> All my bettas have 2.5 gall each. I do 100% water changes every 4 days. But i also make sure no food go to the bottom of the tank ever. My oldest betta about approximetelly 3.5 years old. I live may be a cup of the original water. I don't have filters.
> 
> Sorry i put my post at the same time with Oldfish lady,but i didn't know before how to change them and someone recommended to me 100% so that is what i do since i have them.


Same with me. I never let any old food sink to the bottom, and I don't overfeed him. It really helps to keep the water cleaner for sure.


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## Oldfishlady (Mar 1, 2010)

Its important to remove uneaten food more due to the bad bacteria it can create as it rots and why you don't want to use it to cycle a tank either...it creates a different type of bacteria...anyway.....as I posted.....you are not going to be able to establish a nitrogen cycle on the 5gal unless you add a filter.....but....no worries....you can still successfully keep a Betta in uncycled/unfiltered tanks provided that you make those water changes....lol.....

When you get ready to add him to the new tank-just acclimate him to the chemistry by adding small amount of the new tank water to the holding container over 10-15 min or to his tolerance...the way you should be doing it when making 100% water changes on any of your tanks......


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## Hikari (Jul 12, 2011)

Ok. Thanks. :-D


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## Thunderloon (Feb 6, 2011)

Erm, have to differ with OFL on the point of the tank cycling.

The bacteria WILL form and grow on the waterline in any tank that has an ammonia supply and in small bowls and jars, the fish itself is enough water circulation to qualify.

Generally you need to make sure that a container doesn't cycle through good cleaning practices and not simply rely on the container's small size to somehow protect it. This is where the rapid water change schedule for small bowls comes from.

Under certain water conditions the nitrifying bacteria will even colonize ON your betta's tail and use the skin as the nutrient source. 

Always assume that a cycle WILL happen _if you let it_. 

In the smallest tanks a simple slow bubble sponge filter from Lee's/Tom's will add enough oxygen to the tank and you can simply move it with your boy when you do your tank maintenance cleaning and water changes. It isn't actually necessary to actively filter small volumes but such a simple tool to ensure any cycling that does happen occurs in a controlled manner is a great addition. Lee's sponge plus a little Hawkeye air pump (twist body to control flow type) will last decades and cost about $15.00 total shipped.

As OFL pointed out, some plants can make a huge difference and many perform the same ammonia removal task as the bacteria. There's nothing to stop you from planting some Anubias and transplanting them on the weekly clean-out, as long as you move them into a cup while keeping them under water they recover quite quickly from regular re-plantings.

Plants such as moss balls, algae encrusted ornaments and floating types can also be moved easily and safely.


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## Hikari (Jul 12, 2011)

Thunderloon said:


> Erm, have to differ with OFL on the point of the tank cycling.
> 
> The bacteria WILL form and grow on the waterline in any tank that has an ammonia supply and in small bowls and jars, the fish itself is enough water circulation to qualify.
> 
> ...


How long does it take for a cycle to form in a tank? I'm guessing that the 100% and 50% on my 2.5 gallon weekly is enough to prevent cycling from taking place. Because I don't have a filter, I don't want the tank to cycle.

I was thinking a while back of getting an air stone for the tank set on very low, just to add some more oxygen to the water.


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## ANHEL123 (Jul 21, 2010)

For 2.5 gall 1-50% and 1-100% water changes a week - perfectly fine.


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## Thunderloon (Feb 6, 2011)

If you don't actually sterilize the tank, it WILL cycle, no matter how often you change the water. The bacteria are everywhere, you'll receive them on any live plants you buy, they're on the fish you buy and they'll grow at the water line of anything that penetrates the surface of a tank that contains ammonia. Sulfa drugs and tetracycline both kill the one that eats ammonia but several that eat nitrite are immune to just about everything but heat, ultraviolet and strong oxidization. I commonly have bio-wheels that have set dry for more than a month wake up without needing to recolonize.

You can actually catch cycling bacteria in your eye sockets if your immune system is suppressed. 

So really what you're doing when you do water changes without active sterilization is simply minimizing the cycle. Its my firm opinion that anybody who keeps fish of any kind needs to understand the nitrogen cycle of aquariums because if they don't and it happens aggressively, its a threat to all the fish. Betta are very very hardy creatures and can survive ammonia and nitrite levels that are even toxic to the very bacteria that consume ammonia and nitrite, but the cleaner, clearer and more well prepared the environment you keep them in, the longer they live.

If you don't plan on cycling, DO keep water handy and aging so you can quickly address sudden changes in water quality.


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## Hikari (Jul 12, 2011)

Every single time I do a 100% weekly change I run boiling hot water over the gravel and decor. I scrub the inside of the tank with a sponge with as warm water as I can stand, then I turn the water to boiling and slosh it around the tank, covering all the walls and everything. Would this be enough to sterilize it?

Do you always need to age the water? With the 20% change I don't use aged water, but I warm it up to the right temperature before adding it. With the 100% and 50% changes I always age the water for about 15 to 24 hours.


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## Oldfishlady (Mar 1, 2010)

The biological process to create the nitrifying bacteria require dissolved oxygen in the water...the species of bacterias for the nitrogen cycle can't colonize without it....the fish swimming does not create oxygen....nitrifying bacteria are different that live in the water and out of the water.....

You will not get a stable nitrogen cycle in a system that lack dissolved oxygen or that has limited surface area........


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## Hikari (Jul 12, 2011)

I've always heard that a smaller tank, like under 5 gallons, can't hold a cycle. I also figured that when I did a 100% water change, it killed most of the bacteria, good and bad. I wouldn't want the tank to cycle unless it had a filter and/or plants.


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## Thunderloon (Feb 6, 2011)

I've seen the nitrosomonas colonize surface scum, bubble nests and so forth. The bacteria will bloom in the open water column, there's no way to stop surface transpiration from occurring in a tank unless you maintain a zero air-flow environment that would suffocate your betta with carbon dioxide.

When I cycle tanks by bacteria I usually have a fully colonized media in less than 36 hours, in some cases much less. 

Keep in mind there is no way to keep the bacteria from forming as scum against the glass, its part of the mineral staining we get in fresh water tanks. The only true way to keep a cycle from forming is to use 0.0ppm hardness water and sterilization and you can STILL happen to get some dust into the tank which contains both nitrosomona and nitrobacter resulting in a kick that produces nitrite. I've used test kits on bowls at the 24 hour mark and had positive nitrite and nitrate results.

Every tank, if not sterilized regularly, will begin to cycle and that cycle will grow to the biological load of the tank. My primary point about using biological processing in all tanks is simply that it is never "ok" to let your pet stew in any amount of ammonia or nitrite. It shortens their lifespan.
Setting up a little sponge filter only costs $15.00 and will protect your little one from missed water changes due to the owner being unable to get to the tank or bowl or simply not having the time to spend doing the full clean and sterile.

OFL, I'd say 90% of the dead betta in the western world died from either a surprise cycle in a stagnant bowl or from anerobic bacterium that can infect closed tissue that are normally stopped by a little aeration.

Oxygen is an antibiotic that is safe for continuous use.


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## Hikari (Jul 12, 2011)

It's not the cost of the filter that's the problem, it's that I'm not sure how my fish would react to it. I really don't think he'll like a current, even a very gentle one. And I've always thought you either do the water changes, or have a filter and cycle the tank before adding fish. 

I've read that it's better to do fishless cycling when you're setting up a filter because the first while of cycling is harmful to the fish. So I was thinking if I were just to put a filter in, it would start that harmful cycling process and hurt my betta, and when I do full water changes, the beginning cycling stages that are harmful would just start over again. The main thing is that I don't understand this cycling thing very well and I've read so many mixed opinions about it, so therefore I'm nervous about just sticking a filter into his tank. If plants can work as filtration, I would rather do that if I can find the plants I need. If I can't, I would like to put a filter in, but like I said, I'm nervous to do so because I'm really worried that it would hurt and/or stress my fish.

I actually never miss water changes. I'm extremely diligent about them. I've had this betta for almost a year and a half now and never missed any water changes.


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## ANHEL123 (Jul 21, 2010)

I just think if you have this betta for a year and a half there is something you do right,so don't even change anything in his care. He already adjusted to everything you do and i think if you change something it will stress him out and he can get sick. My betta older then your betta and i never cycle,i don't know how to do that and i don't feel bad,because i don't have any problems with them. I just change them regularly and feed them regularly. I never miss water changes and feeding. I feed them verity of food though including cooked shrimp. I never let food sink to the bottom of the tank. I think you doing good care for your betta so...
Good luck,don't change anything. It like you have grandfather who like to do certain things certain way all his life and now you want to change his life...


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