Aquarium Cycling For Freshwater:  What It Is (And Why It�s Important)

By unknown author


Aquarium cycling is the process that is used to grow a colony of what is known as good bacteria, in an aquarium.  Good bacteria is essential to all aquariums because it literally eats waste products, which would otherwise build up and injure, sicken, or kill the  inhabitants (pets) in the aquarium.

In a freshwater aquarium, there are two kinds of essential good bacteria.  The first kind breaks ammonia down into nitrites, and the second kind breaks the nitrites down into nitrates.  In the normal cycle, aquatic pets go to the bathroom in their own house.  They urinate and excrete directly into the water.  It would be the same as you or I urinating or excreting into the air, in our very own houses.  For the aquarium inhabitants, the most harmful waste product is ammonia.  Nitrites are also very harmful to the inhabitants, but not as harmful as ammonia.  Nitrates, in large quantities, are also harmful to the inhabitants, but not nearly as harmful as either ammonia, or nitrites.

It is important to cycle an aquarium before you add any aquatic pets that you have hope of keeping, in good health.  This is important because in a brand new aquarium, there are not any good bacteria present.  When the inhabitants urinate and excrete, the waste builds up much faster than good bacteria can grow, and ammonia and nitrites damage the gills of the inhabitants, and frequently kill the inhabitants before good bacteria can grow.  Even if the inhabitants survive the ammonia and nitrite spikes which occur before cycling is complete, their gills may be damaged to the point that their lives are terribly painful, and unhealthy.

There are many methods of cycling a new aquarium.  Fishless cycling, Traditional cycling with �starter fish,� and Accelerated cycling with commercial products are the three methods I will discuss.  Whatever method you choose, there are things you can do to speed up the process.

1.  Run the aquarium at a high temperature, up in the low to mid eighties, Fahrenheit.  Only do this if you have no pets in the aquarium which need lower temperatures. The higher temperature leads to faster cycling.

2.  Keep the tank only about 50-65% full.  This creates a waterfall effect as the water leaves the filter, and when the water from the filter hits the surface of the aquarium water, there is a great deal of water turbulence, exposing more water to more air more quickly, and leading to increased oxygenation, and thus, faster cycling.

3.  Keep the aquarium light on 24 hours per day during cycling.  Only do this if you have no pets in the aquarium which need less light, or which need darkness.  The increased light leads to faster cycling.

4.  Use as many air stones and air pumps as you have access to, which will fit in the aquarium.  Keep them all running all the time.  This leads to increased oxygenation, which leads to faster cycling.  Only do this if you have no pets in the aquarium which need calm, or still water.

5.  Keep the filter running the entire time the aquarium is undergoing the cycling process.  This increases water flow, and insures that good bacteria build up in the filter material, both of which lead to faster cycling. 

I will tell you right now that I have a bias toward fishless cycling.  I prefer it, and at the end of the section on fishless cycling, I will tell you the reasons why I prefer it.

You will know when your aquarium has fully cycled, because you will have seen an ammonia spike and a nitrite spike, and you will have zero ammonia, and zero nitrites.

Fishless cycling involves using household ammonia and borrowed good bacteria to initiate the cycle, without any aquatic pets in the aquarium.   There should be no ingredients in the bottle of ammonia that is used for cycling, except ammonia, and/or ammonium hydroxide, and/or water.  It should contain no perfumes, no coloration products, and no surfactants.  The liquid should appear clear, and when you shake the bottle, there should be no fizzing or bubbling.  I used HomeBest Clear Ammonia, which I purchased at a Magruder�s Grocery Store.  You may not know the exact ratio of ammonia to water, in the bottle, because frequently the bottles do not have this information on the label.  Not to worry.  If the ingredients consist only of those listed above, you have the right stuff.

The second thing you will need to initiate a fishless cycle is some seed bacteria.  If you already have a healthy, cycled aquarium then that is the best place to steal some good seed bacteria from.  If you do not have a healthy cycled aquarium, you may need to get some seed bacteria from someone who has a healthy cycled aquarium, or from your Local Fish Store.  What you need is some gravel or substrate from a healthy aquarium (about as much as will fit into a plastic sandwich Ziploc type bag).  It is also good to get some filter pinchings from the pouch in a hang-on-the-back filter, or filter floss or filter sponge or squeezings from a filter sponge, and some water, both from the same aquarium you got the gravel from. 

You will also need a testing kit for ammonia, nitrites, and nitrates.

During a fishless cycle, the water should not be changed until the cycle is complete, and you are getting zero ammonia and zero nitrite readings.  The only exception to this would be if you accidentally add too much ammonia during the process.  If you accidentally do this, you will see either ammonia or nitrites off the charts at 6-8 ppm, and they won�t come down without a water change. So if this happens, do a 50% water change, and start the fishless cycle process over again. Or, if you know the error you made that caused you to add too much ammonia, calculate the number of drops you should be adding, and add that amount, according to the recipe, which follows, in the next paragraph.

To perform a fishless cycle, add 95% of the seed gravel or other substrate from the healthy aquarium to the gravel or other substrate in your new aquarium.  Then take the remaining 5% of the seed substrate material, and put it into a new nylon stocking, which you have pre-washed, in cold tap water.  Then cut most of the stocking off, so you have a little stocking pouch, full of seed substrate material.  Then tie the pouch closed, or seal it somehow, so you have a closed pouch of seed substrate material.  If you are using a hang-on-the-back filter, drop this pouch of seed substrate material into the filter.  Make sure the pouch does not stop water flow through the filter entirely.  Then, add some filter material pinchings or squeezings into the water in the filter and into the water in the aquarium. 

Next, you will add ammonia.  You will need to put the ammonia into a clean dropper bottle, if it didn�t come in one.  Label that dropper bottle immediately, with the word �AMMONIA� in capital letters.  Simply add drops of ammonia until your ammonia reading goes up to 5.0 ppm, which is very high.  It took me about 30 minutes of adding ammonia and then testing for ammonia and then adding drops and then testing for ammonia until I got the 5.0 ppm ammonia reading.  Keep track of the total number of drops it took for you to get the desired 5.0 reading. After the first day in which you add ammonia, you should test for ammonia and nitrites every day.  Then, every day, after testing for ammonia and nitrite, add the same number of drops of ammonia until you see a nitrite reading.  On the first day that you actually see a nitrite reading, add half the number of drops of ammonia that you added on the first day, and keep adding that amount every day until you test and have zero ammonia and zero nitrites.  At that point, you will need to do a massive water change. 

I did a 99% water change, and I still had to do a few more partial water changes the same day, to get rid of the high nitrates in the tank.  A fishless cycle uses much more ammonia then would normally develop with other methods, and therefore the leftover nitrates can be quite high.  My nitrate reading was 160 ppm when I was done with my first fishless aquarium cycle.  Don�t add any pets to the aquarium until your nitrate reading is 10 ppm or less.  You can do multiple water changes in the same day, until the desired nitrate reading of 10 or less is achieved.  This works because the good bacteria is in the substrate, and in the filter, and remains after the water change.  When you have zero ammonia, zero nitrites, and 10 or less nitrates, your aquarium is fully cycled, and ready to house your aquatic pets.

It took me three and a half weeks to accomplish my first fishless cycle.  But someone who follows the above recipe, and uses all the tips to speed up the cycling process would probably be able to get it done in 2 weeks.


The reasons why I prefer fishless cycling:

1.  Fishless cycling is faster than conventional cycling with fish.  This is because in fishless cycling, much more ammonia is used than would be generated by the waste of fish.  This leads to a faster build up of good bacteria in the aquarium.

2.  When you are finished with a fishless cycle, you can fully populate the aquarium with pets right away, without risk of ammonia and nitrite spikes.  This is because in fishless cycling, much more ammonia is used than would be generated by the waste of fish.  This leads to the growth of a much larger colony of good bacteria than would be grown by traditional cycling with fish.  After a traditional cycle with fish, aquarists need to add their pets slowly, over time, to avoid adding too high of a bio-load too quickly and getting an ammonia spike or a nitrite spike.  After a fishless cycle, the colony of good bacteria is large enough to fully populate the tank with inhabitants, right away. 

3.  With fishless cycling, there is no need to kill, injure, sicken, or damage the gills of any �starter� fish.  It�s just kinder.

It is important to note here, that as a general rule, one should not add more than 1 inch of fish for every gallon of tank size.  This is a general rule, for �thin� fish.  If you have �fat� fish, you may need to add no more than half an inch of fish for every gallon of tank size.  And if you have very large fish, like Oscars, you may need to have even less fish-inches per gallon of tank size.  If you do overpopulate a fully cycled tank, then ammonia and nitrite will still build up, and injure, sicken, or kill the tank�s inhabitants. 

Traditional cycling with fish involves getting usually 2-4 small, hardy, disposable fish, and putting them in a brand new tank.  They are there to urinate and excrete into the water, and give the good bacteria food (waste) to dine on.  This method of cycling typically takes 4 to 6 weeks.  Many starter fish do not survive, and those that do often have no quality of life left.  Their gills are damaged.  After you have cycled traditionally, with fish, you can start to add pets to your aquarium, slowly, one or two inhabitants at a time.  You would need to wait a few weeks after adding your first 1-2 inhabitants before adding the next 1-2 inhabitants.  This prevents an ammonia spike or a nitrite spike, which could kill the inhabitants.  For decades, traditional cycling with fish was the only common method used to cycle aquariums.  It is a proven method, and it will work.  In my opinion, it is just not the best, or most efficient, method.

Accelerated cycling, enhanced with commercial products that claim to add good bacteria directly to the aquarium, and thereby cycle the aquarium overnight have been developed, and are now on the market.  BioSpira, from Marineworld Labs, and Cycle, from Hagen, are two of the most frequently used.  Even though others have reported success with these products, I do not recommend them because I have never seen them work well.

In sum, for the sake of your new aquatic friends, it is essential to fully cycle a new aquarium before adding the new inhabitants, in order to ensure their health, safety, comfort, and happiness.  For the reasons outlined in this article, I recommend fishless cycling above all other methods, in conjunction with the five ways I mentioned to speed up the cycling process.