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Cycling Fishless
240 gallon acrylic FW tank cycled fishless.
How A Tank Cycles
As we all know, *ammonia* is what gets the nitrogen cycling established in an aquarium. Fish, by breathing and passing waste, create ammonia. Ammonia is however, highly toxic to fish and many species will die with even a small amount of it present.
When ammonia levels rise (in sufficient quantities to cause fish stress or even death), "good bacteria" called Nitrosomonos, begin establishing themselves in the aquarium. This bacteria thrives on ammonia, converting it through oxidation to less toxic *nitrite*.
Ammonia ----> Nitrosomonos (good bacteria #1) converts Ammonia to -----> Nitrite
Although nitrite is less toxic than ammonia, it is still bad news to fish. So while the ammonia levels in the aquarium may be dropping to safe levels, the fish - already stressed and weakened from the ammonia poisoning - now have to endure high nitrite levels. Finally after a couple more weeks, the last stage of the nitrogen cycle kicks in and the second type of "good bacteria" (Nitrobacter) start colonizing.
Nitrite ----> Nitrobacter (good bacteria #2) converts Nitrite to ----> Nitrate
Nitrobacter bacteria feeds on nitrite, turning it into harmless *nitrate*. That "a" makes all the difference. Once nitrAte starts being created, the nitr_i_te levels drop. Eventually to zero. This is a "cycled" tank.
But this doesn't happen soon enough for your fish!
This whole process (called a 'biological filter') takes several weeks to establish itself in a new tank. Once established, it keeps the water free of pollutants. However, while it is establishing itself many aquarists, especially those new to the hobby who have no understanding of the nitrogen cycle, lose countless fish. If they don't die directly from ammonia or nitrite poisoning, they often succumb to any handy disease. A new aquarist will say, "I don't know what happened! The water was clear and clean, and all the fish looked healthy for 2 weeks then I went in and they were all dead!" or "they all came down with ich" etc. Sometimes a few hardy fish will make it. Some people advocate using "cycling fish" -- fish that are known to be able to withstand the high ammonia and nitrite levels. After the tank is cycled, these fish are often discarded or traded back to the fish store. :(
Those with more experience know that they must do lots of small to moderate water changes during the cycling process to keep ammonia and nitrite levels tolerable. Even after a tank is cycled fish must be added very slowly (one every few weeks) to give the biological filter a chance to keep up with the increased ammonia being added to the water.
All in all, cycling a tank can create a nervous wreck of the aquarist, to say nothing of the fish.
But that was then...
In January of 1999 Chris Cow, who holds a PhD in organic chemistry, posted a paper online regarding fishless cycling. Though there are quite a few sites who post this method now, as far as I know he was the first to put the theory forward and it is he who deserves the credit. He got the simple, brainy idea to add ammonia to a fishless aquarium in order to establish the nitrogen cycle before any fish are introduced at all. This not only saves the fish from stress and death, it saves the aquarist from stress as well: the stress of worrying about their fish and doing constant water changes to reduce ammonia and nitrite levels while waiting for the tank to cycle.
Chris Cow's experiment worked wonderfully, and has been used by hundreds of aquarists since. In fact, it is rapidly becoming The WayTM to cycle a tank.
In short, the method is to add 4-5 drops of pure ammonia per 10 gallons of water, once a day until the tank is cycled. Ammonia (of course) will be measurable right away, and nitrite will become measureable after several days. As nitrite starts to spike, the ammonia spike should drop, (even though you will still be adding it every day). When nitrite and ammonia are both at zero, the tank is cycled. At this point a substantial water change of 25% or more is advised, then add your fish. As always, make sure the water in the tank is comparable to the water where your fish are coming from. From this point forward the fish will be providing the ammonia through urination, decaying food, etc. Do not add ammonia once fish are added.
Make sure to use pure ammonia -- no added detergents or colors. Chris has a good test -- he says to shake the ammonia if you aren't sure if it's pure. Ammonia with additives will foam up. Pure ammonia won't. I've used Goodwin's and Whirl. Both are available at drug stores and grocery stores.
I have cycled four tanks fishless using his method. I have not been able to cycle a tank in 4 or 5 days as some have reported. In my case it has taken 5-6 weeks, but when there are no fish to be worried about, the time factor doesn't matter. I will say Chris recommends using a simple declorinator/de-chloraminer while cycling fishless, rather than products like Prime or AmQuel which "sequester" ammonia by converting it to non-toxic ammonium. Chris' concern is that sequestered ammonia (i.e. ammonium) may be harder for bacteria to process, and therefore using these products while cycling fishless may slow the process.
I didn't heed this advice for 2 reasons; the first being I had Prime and AmQuel on hand and didn't want to go buy a ton (cycling 260 gallons of water) of a third type of conditioner that I would never use again after the tank got cycled. And secondly we know biobeds are unaffected in cycled tanks by products like AmQuel and Prime, so I figured sequestered ammonia must be available to the bacteria just as much as unsequestered. My tanks did cycle but the length of time it took could be attributable to this factor. If you want your tank to cycle as soon as possible, you might try heeding Chris' advise. :)
The greatest thing about fishless cycling is that it is humane -- you don't have to worry about your fish while cycling. The second greatest thing is that you can add a full complement of fish afterwards, because you will have a fully matured biobed capable of biofiltering a fully stocked (not overstocked) tank. If you plan on getting territorial fish who are better added all at once, this method is ideal. (Note: Once you add fish to the tank the biobed will adjust to the fishload, so in the future if you add new fish, do it slowly to give the biobed a chance to catch up to the new bioload.)
In addition to these advantages, there are also others: it is easy to keep an extra filter cycled on a plastic container that is fed daily drops of ammonia. You can also keep a hospital tank cycled this way if you have the room to have an extra tank set up. Or let's say you have a situation where you know you're going to have to tear down a tank and filter (in the case of severe disease for example), you can cycle a pristine filter ahead of time using a plastic bucket or container. This will avoid you having to go through recycling the tank once you clean it. You can put the pristine cycled filter immediately on the newly cleaned tank, thereby giving it a fully established, totally clean biobed. Now you can disinfect and recycle the original filters at your leisure. (If you keep a filter cycled in a plastic bucket or tub, keep in mind that the bacteria which makes up the biobed will be dormant in temps below 68F or so, so placing a heater in the bucket or container would be a good idea. 72F is fine once it's cycled, but keeping it up around 80F while cycling will make the process go faster.)
In conclusion, I would never cycle a tank with fish in it again and I thank Chris Cow for his articles. I'm sure countless fish would thank him too, if they could.
Here are those advantages again, (and this is just a partial list!):
- Fishless cycling is humane.
- Reduces stress of the aquarist as well as the fish.
- You can add a full complement of fish all at once, as soon as the tank is cycled. This is handy for territorial fish like cichlids that are better added together, but it is also good for anxious aquarists who don't want to add fish slowly with weeks between each purchase.
- You can keep an emergency filter cycled easily on a plastic container fed with daily drops of ammonia.
- You can easily keep a hospital tank cycled, without having to keep a fish in it.
- You can cycle filters ahead of time if you know you're going to tear down a tank (e.g. due to disease).
Pictures and text copyrighted 2001-2007 Tanked. All rights reserved.
If you're new at this it's safer and easier to just think in terms of, 'all ammonia is toxic'. However to get technical about it, if the pH of your water is acidic (i.e. below 7.0), then ammonia gets converted to a non-toxic state. But even if your tap water comes out at pH 6.8 or less, this doesn't mean that your fish won't have a problem waiting for the tank to cycle. For one thing, water's pH can rise as it sits; and aeration created by pumps and air stones can also make it rise. Also, even if the water is acidic, the next stage of the cycling process involves nitrite which is toxic at any pH. (Most people do not have acidic water out of the tap anyway.) It may be worth noting, since most of us have alkaline tap water with a pH greater than 7.0, that the higher the pH, the more toxic ammonia becomes. That is, the same amount of ammonia at 7.2 is more toxic at pH 8.0. Higher temperatures also increase toxicity. Therefore, the worst case scenario is a high pH, coupled with high temps. The good news is, once a tank is cycled you rarely have to worry about ammonia, unless the biofilter somehow gets compromised, or you suddenly add several new fish to an established aquarium. (Use your browser's "back arrow" to go back to what you were reading.)
Nitrate, a natural fertilizer, is absorbed by plants in the freshwater aquarium; however most people don't have enough plants to absorb all of the nitrate which builds up in the closed system of an aquarium, especially at high stocking levels. Weekly or bi-weekly water changes are usually necessary to keep nitrate down to desireable levels. For more information, see: Tools For Managing Nitrate in Freshwater Aquariums. Or use your browser's "back arrow" to go back to what you were reading.
Pictures and text copyrighted 2001-2008 Tanked. All rights reserved.
