Startup cycle

Call it cycling, nitrification, biological cycle, startup cycle, break-in cycle, or the nitrogen cycle. No matter what name you use, every newly set up aquarium goes through a process of establishing beneficial bacterial colonies. Older aquariums also go through periods during which the bacterial colonies fluctuate. Failure to understand this process is the largest contributing factor to the loss of fish. Learning what it is, and how to deal with critical periods during the nitrogen cycle, will greatly increase your chances of successful fish keeping.

The Waste Problem
Unlike nature, an aquarium is a closed environment. All the wastes excreted from the fish, uneaten food, and decaying plants stay inside the tank. If nothing eliminated those wastes, your beautiful aquarium would turn into a cesspool in no time at all.

Actually, for a short period of time, a new aquarium does become a toxic cesspool. The water may look clear, but don't be fooled. It's loaded with toxins. Sounds awful, doesn't it? Fortunately bacteria that are capable of converting wastes to safer by-products begin growing in the tank as soon as fish are added. Unfortunately there aren't enough bacteria to eliminate all the toxins immediately, so for a period of several weeks to a month or more, your fish are at risk.

However, you need not lose them. Armed with an understanding of how the nitrogen cycle works and knowing the proper steps to take, you can sail through the break-in cycle with very few problems.

Stages of the Nitrogen Cycle
There are three stages of the nitrogen cycle, each of which presents different challenges.

Initial stage: The cycle begins when fish are introduced to the aquarium. Their feces, urine, as well as any uneaten food, are quickly broken down into either ionized or unionized ammonia. The ionized form, Ammonium (NH4), is present if the pH is below 7, and is not toxic to fish. The unionized form, Ammonia (NH3), is is present if the pH is 7 or above, and is highly toxic to fish. Any amount of unionized Ammonia (NH3) is dangerous, however once the levels reach 2 ppm, the fish are in grave danger. Ammonia usually begins rising by the third day after introducing fish.

Second stage: During this stage Nitrosomonas bacteria oxidize the ammonia, thus eliminating it. However, the by-product of ammonia oxidation is nitrite, which is also highly toxic to fish. Nitrites levels as low as low as 1 mg/l can be lethal to some fish. Nitrite usually begins rising by the end of the first week after introducing fish.

Third stage: In the last stage of the cycle, Nitrobacter bacteria convert the nitrites into nitrates. Nitrates are not highly toxic to fish in low to moderate levels. Routine partial water changes will keep the nitrate levels within the safe range. Established tanks should be tested for nitrates every few months to ensure that levels are not becoming extremely high.

Now that you know what is happening, what should you do? Simple steps such as testing and changing the water will help you manage the nitrogen cycle without losing your fish.


What To Do
The key for success is testing the water for ammonia and nitrites, and taking action quickly when problems occur. To aid in tracking the status of your aquarium, links to charts for logging your tests can be found under the charts section of this page. Each chart shows the danger zones and offers steps to reduce toxins before they result in loss of your fish.

Test for ammonia: Begin testing on day three after adding the fish, and continue every day until the ammonia begins to drop. After it begins to fall, continue testing every other day until the ammonia reaches zero. Using the chart provided, plot the ammonia levels. Should ammonia reach the danger zone, take steps as shown on the chart. If at any time fish show signs of distress, such as rapid breathing (gilling), clamped fins, erratic swimming, or hanging at the surface for air, take immediate action to lower the ammonia level. Chemicals such as Ammo-Lock will quickly neutralize toxic ammonia.

Test for nitrites: Begin testing one week after adding the fish. Continue testing every second or third day, until it reaches zero. Using the chart provided, plot the nitrite levels and take steps as shown on the chart if nitrite reaches the danger zone. If at any time fish show signs of distress, such as rapid breathing or hanging near the surface seemingly gasping for air, test for nitrite. If levels are elevated perform an immediate 25-50% water change and test daily until levels drop.

What Not To Do
# Don't add more fish - wait until the cycle is completed.

# Don't change the filter media - the beneficial bacteria are growing there. Don't disturb them until they have become well established.

# Don't overfeed the fish - when in doubt underfeed your fish. Remember that anything going into the tank will produce wastes one way or another.

# Don't try to alter the pH - the beneficial bacteria can be affected by changes in pH. Unless there is a serious problem with the pH, leave it alone during the startup cycle process.


Q: Will adding bacteria solutions, such as those available at pet shops, eliminate the break-in cycle?
A: No, due to lack of an ongoing supply of ammonia and oxygen, the nitrification bacteria cannot survive in a bottle for a prolonged period of time. There are manufacturers making special preparations of the nitrogen fixing bateria. However, what you see on the shelf at the store is simply the bacteria needed for the first stage of the cycle, not nitritfying bacteria. Since the bacteria needed for the first stage of the cycle is already present in the tank once it is set up, there is no need to purchase more of what you already have.

Q: Will changing the water lengthen the time of the cycle?
A: It is true that partial water changes decrease the level of ammonia and nitrites, which in turn triggers less growth of the bacteria that feed on them. That doesn't mean you shouldn't perform water changes. If the ammonia or nitrite levels become too high, the fish will die. That means that partial water changes should be done whenever toxins reach dangerous levels, even if it means if it slows down the completion of the cycle.

Q: Won't filling the tank and letting it run for several days before adding the fish get the nitrogen cycle going?
A: No, the cycle doesn't start the instant the tank is set up. An ongoing supply of ammonia must be present for the process to begin. That only happens if fish are in the tank, or ammonia is added regularly, as is done in "fishless cycling".

Q: A friend started a new aquarium and didn't test the water or do water changes. In spite of all that, he didn't lose a single fish. If he can get away with that, why can't I?
A: Your friend probably had the magic combination of several of these key factors; relatively few fish, very hardy fish, a large aquarium, minimal feeding, live plants, and water with a low pH. While it is possible to get through the startup-cycle without doing anything, it is not wise to leave it to chance. The only way to be sure you don't lose fish is to test your water to monitor what’s happening, and take steps if ammonia or nitrite levels soar too high.


Ammonia Check :


NSTRUCTIONS
1 Begin ammonia testing on third day after aqaurium has been set up.
2 Plot test results on chart daily until values drop to zero.
3 If results are in the shaded areas, take appropriate steps as shown.
4 If at any time the fish show signs of distress immediately take steps shown for > 2.0

Water Changes
Use water that has a lower pH and the same temperature as the aquarium water.
When changing water remove any uneaten food and other debris.

How to Lower pH
Filter water using peat.
Use water with a lower pH when doing water change (R.O water, or distilled water).
Use a pH lowering agent such as pH Down.

Chemicaly Neutralizing Ammonia
Use a commercially prepared chemical such as Ammo-Lock, according to manufacturers instructions.

Ammonia in ppm :

0.25 - 1 ppm : Perform 25% water change and reduce feeding by half

1 - 2 ppm : Perform 25 to 50% water change and continue reduce feeding and observe the fish whether in distress or not.


> 2ppm - Perform 50% water change, Chemically neutralize ammonia
Lower pH below 7.0,Withold feedings until level drops




Nitrate Check :


INSTRUCTIONS
1 Begin nitrite testing on seventh day after aqaurium has been set up, or when the ammonia begins to drop
2 Plot test results on chart daily until values drop to zero.
3 If results are in the shaded areas, take appropriate steps as shown.
4 If at any time the fish show signs of distress immediately take steps shown for > 1.0

Water Changes
When changing water remove any uneaten food and other debris.
Water changes are the only way to reduce Nitrites. If levels are extremely high, multiple water changes
may be necessary to bring the level to a safe range



Nitrate in ppm :

0.1 - 0.5 : Perform 25 % water change,Reduce feedings by half

0.5 - 1 ppm : Perform 50 % water change,Reduce feedings by half n Add 1/2 oz salt per 1 gallon water,Increase aeration.

> 1ppm : Perform 50 % water change, Retest after water change, if not below 1.0, change water again.



http://freshaquarium.about.com/cs/biologicalcycle/a/nitrogencycle_3.htm