Tropical Fish Keeping - Aquarium fish care and resources

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Jamesy14 04-18-2009 05:26 AM

hey im new and was wiondering what cycling was and how you do it thanks

willow 04-18-2009 05:55 AM

hello and welcome.
Cycling a tank takes 2-8 weeks. It takes 5-9 days for the nitrosomonas bacterium to establish itself at a level to handle the available ammonia (its food), and once it starts converting the ammonia to nitrite it takes several days for the nitrobacter bacterium to establish itself at a level to handle its food, nitrite. At some point these levels will be established and the ammonia and nitrite will from then on always be 0 when you test, and you know the tank is then cycled. However, you can throw the wrench into this process by adding more to the bio-load, as more fish, overfeeding, dead fish and plants not immediately removed, etc. Doing any of these things will produce more ammonia than the nitrosomonas can consume and they will start to multiply, and similarly the nitrobacter. Provided the increase is reasonable for the size of tank, the bacteria will be able to reproduce quickly and you won't notice anything. It's only when the extra load on the system is too great at once that a mini-cycle will occur, stress the fish and so forth.

The bacteria always exist at the number needed to consume their food (ammonia or nitrite). Adding a new fish increases the ammonia, and the nitrosomonas multiply to handle it, then the nitrobacter do the same when the extra nitrite appears.

this has been written by Byron,a member here.
(an ihope he dosen't mind me quoting him.)
i hope this has helped you.

Byron 04-18-2009 12:56 PM

Hey willow, I thought those words seemed familiar! No problem you citing me. I will just add something for Jamesy14's benefit, as I noticed more from him in another thread.

The "ammonia" has to come from somewhere to start the cycling process. You can cycle with fish (they always produce ammonia by the act of respiration, and ammonia results from their waste and any decaying/dying animal or plant matter in the tank), but they need to be hardy and few. You are looking at a 10g or 20g tank if memory serves me (I would go for the largest you can afford and house, the 20g in this case, you will have fewer problems and be happier in the long run as you'll fit a few more fish in it). You mentioned danios, they are good fish to cycle. In a 20g you could put in three danios, and always add a product called "Cycle" (or a similar product, there are others I don't know the names of) to ease the stress on the fish. "Cycle" is a bacteria starter culture (so to speak) that "seeds" your tank immediately and gets the nitrogen cycle going faster, but it still takes anywhere from 2 to 8 weeks to complete. Don't put any more fish in for this period, not until your ammonia and nitrite readings are "0" for a couple of days running, then you can add a couple more fish, wait a few days for the bacteria to multiply accordingly, and then add a couple more, etc.

While the cycling is starting, you do the normal weekly partial water change (you must change 25-35% of the tank water once a week to maintain healthy fish) but do not vacuum the gravel as you would during a normal water change after the tank has cycled. The good bacteria will colonize everything in the tank including the substrate, and you don't want to remove any while they are still establishing themselves during the cycling process. Similarly, do not clean or rinse the filter during the 8 weeks, it will not need it and again this will kill the good bacteria. Once the tank is cycled, the filter media can be rinsed (in water from the tank, not tap water to avoid the chlorine killing more of the bacteria) when needed to remove suspended particulate matter, but the media should not be replaced unless it is literally falling apart or has lost its usefulness.

You should buy yourself a test kit that will test ammonia, nitrite and pH at a minimum. API are good test kits, and there is one that has these tests plus nitrate, that would be a good one to buy. Tests for ammonia should be done daily at the beginning of the cycle; you will see the ammonia rise and then fall until it reads "0" in a few days. When the reading starts to decline, start testing for nitrite each day; it will also rise and then fall to "0" after a few days. At that point, both ammonia and nitrite should read "0" from then on.

The nitrate is the third part of the nitrogen cycle in an aquarium, and you will always have nitrate in a tank. Plants (if you have live plants) will consume some of it, and there are other bacteria that need it for other biological processes that are always going on in a healthy aquarium. The partial water change each week will remove more of it. Most aquarists recommend keeping nitrates between 10-20 ppm, and not above 40 ppm. I have thickly planted and heavily stocked aquaria, and my nitrate reading in both is consistently 5-10 ppm. You shouldn't have to worry about nitrate, it is not toxic to fish except at excessively high levels (some fish have trouble with nitrate at 40ppm, others way higher, which is why 40ppm is usually given as the maximum) and you won't have these unless you neglect the weekly partial water change.

willow 04-19-2009 03:18 AM


dramaqueen 04-19-2009 07:33 AM

Good info.

Jolly Jerry 04-19-2009 09:03 PM

I must be lucky. I didnt know anything about cycling a tank. I just added water let it sit for two days then hooked filter and heater up and added my fish. They have been in there for two weeks now and are doing fine. I quess I was lucky. After reading this I will start changing the water on a weekly basic.


willow 04-20-2009 02:53 AM


Originally Posted by Jolly Jerry (Post 189258)
I must be lucky. I didnt know anything about cycling a tank. I just added water let it sit for two days then hooked filter and heater up and added my fish. They have been in there for two weeks now and are doing fine. I quess I was lucky. After reading this I will start changing the water on a weekly basic.


hello and welcome.
i'm glad that your fish are ok,will you be able to post any pictures of
your set up and fish. ?

Jolly Jerry 04-20-2009 08:55 AM

I sure can. Give me a couple of days.


Byron 04-20-2009 09:54 AM


Originally Posted by Jolly Jerry (Post 189258)
I must be lucky. I didnt know anything about cycling a tank. I just added water let it sit for two days then hooked filter and heater up and added my fish. They have been in there for two weeks now and are doing fine. I quess I was lucky. After reading this I will start changing the water on a weekly basic.


Yes you were lucky indeed. Read the several threads from other first-time fish keepers in this forum and note how many first post because their fish are starting to die off and they don't know why, and it's always the cycling.

There are some reasons why one can sometimes be lucky like this. The pH of the water--in acidic water (pH below 7) ammonia converts to ammonium and this is far less toxic to fish; in an alkaline tank (pH above 7) the ammonia remains ammonia and if you reviewed all the posts about fish deaths from new tank syndrome you will note that where it is given the pH is alkaline. Of course, the nitrite part of the cycle has to establish itself, and you may not have gone through this part yet in only two weeks. Second, the size of the aquarium--the larger the tank the easier the cycling is on the fish. Third, the number of fish and what species (some are better able to withstand cycling). And fourth, "doing fine" is what you/we observe, not the state of trauma the fish may be feeling; that fact that they are still swimming around and eating doesn't mean they are not stressed out--and this may or may not come back to claim them within the next few weeks. It would be interesting to know your water parameters (pH, ammonia, nitrite, nitrate) but I suspect you don't have a test kit yet--something you should certainly acquire.

A partial water change of minimum 25% up to 40% every week is in my view absolutely mandatory. I have written at length on the benefits of this elsewhere on this forum (as have many others), but as you are new to this here is an excerpt that will explain a bit more about this, in addition to what I wrote in the previous post.

The aim is to maintain consistent water quality permanently. This is not as impossible as some may think. There are fluctuations that occur naturally, in nature and in our aquarium. Fish have evolved to adapt to these minor fluctuations. This involves temperature and pH (there are diurnal fluctuations both in nature and in an aquarium), hardness, and dissolved organics in the water. Fish are very closely tied to their environment. As an example, fish take in water through their cells by osmosis. The fish must adjust its internal pH to equal that of the water passing into its cells. In an excellent article on "Fish Growth vs. Tank Size" in the December 2006 issue of TFH, Laura Muha notes that "Both salinity and pH affects a fish's growth rate because they affect how hard a fish's body must work to maintain its physiological equilibrium--that is, the complex chain of internal chemical reactions that keep the pH of its blood steady, its tissues fed, and its immune system functioning. When pH and/or salinity stray outside the ideal range for any given species, the fishes' bodies must work harder and use more energy to maintain this equilibrium." Having fluctuating water conditions means the fish is constantly having to adjust its metabolism, and this stresses the fish and can lead to poor health, disease, and even death if not corrected. The point of regular water changes is establishing an equilibrium in the tank and therefore in the fish, resulting in healthier and happier fish. Changing 25-40% of the water every week is maintaining such a balance, because it ensures that the pH will remain relatively constant, along with the levels of minerals in the water, and the nitrate level. In addition, it is a fact that fish urinate regularly and without water changes there is no means of removing/diluting this, and that is not healthy for any fish.


Jolly Jerry 04-20-2009 10:24 AM

Thanks for your advice. I will start with the water change this afternoon. I have a small 10 gallon tank but will have a 55 gallon tank soon. Im picking up a test kit today. I will follow the proper directions as to cycle my tank. I do thank you for your time and knowledge.


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