Nitrogen Cycle: The Basics.

[ron v]

I thought I would start a thread about the persistent problem of cycling a new aquarium. Maybe ya'll could add to it and we could "sticky". Newcomers could then be referred here instead of having to explain it over and over.

Cycling is a process that all aquariums must go through before they are ready for fish. I personally am convinced that most new aquarists drop out of the hobby, in fustration, because they do not understand or respect this event. It is a biological process that normally takes place during the first four to six weeks and involves the establishment of bacteria that consume toxic ammonia and converts it into nitrite ( which is also toxic ) and ultimately into nitrate which is relatively safe.

Set your tank up with heaters filters ect. and treat water for chlorine.
To begin cycling, your tank must be supplied with a source of ammonia. There are a couple of way to do this. Probably the simplest way is to add a small fish or two. Ammonia will be produced and the cycling process is off and running. These fish will be exposed to a high level of toxic ammonia and nitrite during the cycle and should be considered expendable, in my opinion. Eventually the bacteria will develop to the point where all ammonia produced by your two fish will be converted, almost immediately into nitrate and your tank is cycled and ready to sustain those two fish. If more fish are added, more ammonia is produced and more bacteria must develop to handle the new bio-load. This is called a mini-cycle and takes place in a relatively short period of time.

You can track the process of the cycle with commercially available test kits. You will need one for ammonia, NH3, nitrite, NO2 and nitrate NO3. During the first 2-3 weeks, the ammonia will continue to rise. No nitrite or nitrate will be detected. Nitrite will then start to show up and ammonia will decrease. Eventually nitrite will decrease and nitrate will be detected. When ammonia and nitrite both drop to zero, you are done. A water change will dilute the nitrate and everyone will live happily ever after.....Except those first two fish. Ammonia and nitrite are deadly poisons and it is common for all of your starter fish to die from exposure. It is also a fact that damage to gills caused by ammonia is, to some degree, permanent even if the fish survives.

Cycling technique number two is called "fishless cycling" and involves puchasing pure ammonia and adding it to the aquarium every day. The cycle proceeds exactly the same way and can be tracked the same way with your test kits.

Set your tank up as before with heater, filter, etc. But no fish. Instead add pure ammonia until your ammonia test kit reads 3.0 ppm. Keep checking your ammonia level every day and add as necessary to keep the 3ppm. It may take several days. Nitrite will start showing up and you will need to add more and more ammonia to keep it a 3ppm. Keep adding until ammonia and nitrite both drop to zero after 24 hrs. Your nitrate will be extremely high at this point. A 90% water change will dilute the nitrate to an acceptable level. You are done and can now completely stock your tank.

The advantages of fishless cycling are numerous. First and foremost is that you don't have to sacrifice any fish. Another is that you can fully stock your tank as soon as the cycle is complete. The 3 ppm ammonia that you add each day is far more than a tank full of fish can produce, so it will be ready for more fish than you could put in. The massive dose of ammonia may also decrease the length of time for the cycle to complete.

This is an oversimplication of a complex event and I'm sure much can be added but I'm tired of typing. I would welcome your comments, and together maybe we can create something that will be of help to a new hobbyist or two.

[Alin10123]

Thanks for this Ron. When i first started i wish i would've done the research instead of just listening to the folks at the LFS who told me that my tank was ready. I'm sure this will help a LOT of the new folks out.

By the way, another way to do a fishless cycle is to add a source of ammonia that isn't ammonia. For example i did the shrimp method. I basically just dropped a ****tail shrimp in the tank for about 5 days and my test showed a huge increase in ammonia. I took the shrimp out before it started to stink up the tank. Then i added some fish flakes in order to keep up the ammonia source while the flakes rotted away at the bottom. My 55 gallon tank cycled in exactly 1 month. Of course i also took the filter media out of my cycled 20 gallon and let it sit in my 55 for about an hour. But i didn't do that until i was positive of an ammonia source.


thanks again for the info.

[mousey]

Well we could also add that most cities and towns add Chloramine to the water supply and it needs to be removed.make sure you get a conditioner that handles that as well as plain chlorine.
In my opinion fish are NOT expendable in cycling the tank. Every life is valuable. therefor as the ammonia starts to rise you can add a product such as Ammo lock to neutralize the ammonia into a non toxic form. When the nitrite starts to rise the addition of aquarium salt will prevent the fish from being stressed by that toxin and they usually come sailing thru.
I used the same platy to cycle 3 tanks this way and she lived to just over 2 years.
mousey

[ron v]

Originally Posted by mousey In my opinion fish are NOT expendable in cycling the tank. Every life is valuable.

Any fish used to cycle an aquarium will likely be damaged in the process. So they SHOULD be considered expendable.

"Every life is valuable" .....SO TRUE. That is why I wish everyone would "fishless" cycle and not expose these poor creatures to ammonia/ nitrite poisoning.

Ammo lock, and other products, will bind ammonia and salt will help fish withstand nitrite poisioning. Water changes will help also. But they are not perfect answers. How much ammo lock to add. How often? Does ammo lock bind the new ammonia produced after it has been added. How much ammonia is in my tank ( a regular test kit won't detect the bound ammonia ). How do I track the progress of my cycle? How much salt do I add for nitrite..... I guess the last question might be... With all this poison in my water, am I sure that my fish "which I don't want to consider expendable" are really OK????? Is all this stuff I'm adding really working????

Why not be patient for 4-5 weeks, use pure ammonia to cycle your tank and avoid the problems.

[chrisinha]

I have a question concerning the nitrogen cycle. I have been helping a friend to get her tank cycled and she's been having problems with lowering her nitrItes (they are always on 2.5ppm). I told her to increase the amount of water changed to 35 - 40% and she asked me a question I can't answer. She's wondering if the thing with cycling is to "build" good bacteria, wouldn't the water changes be a drawback?

Can someone here help me answer that?

[leveldrummer]

the water changes dont remove much bacteria, but your trying to get everything low enough so that it doesnt harm fish. the bacteria will do just fine, but the fish wont, untill the bacteria is there. the bacteria grow on the surfaces of the tank, not in the water itself. if you dont vaccum the gravel, taking out water shouldnt remove any bacteria at all.

[chrisinha]

Thank you so much for your response!!

[TheOldSalt]

If her nitrites are "always" at 2.5, then there may be a problem somewhere in the system. Incomplete nitrification can be caused by a clogged filter or a lack of oxygen. Is the gravel really deep or anything?
If the tank is still new & cycling, then don't worry about it, but if it's over 3 months old, then have her take a good look at things.

[chrisinha]

Her tank has been running since jan 5, so it's still cycling. I think one of the problems is because it's too small. it' a 5 gallon tank. i've always found the smaller the tank the harder it is to cycle, but that might be just me.

[ron v]

Change water to keep the level of nitrite down to about 1. The high level of nitrite is actually killing your bacteria.

[chrisinha]

Oh she's been changing 25% of the water every day and nitrites dont get lower

[ron v]

I wonder about the test kit. If you change 25% of the water, it should dilute the concentration by 25%.

[bpswim90]

I'm going to be moving some goldfish from my 10 gallon tank to a pond outside later this spring. Afterwards I want to keep my tank in shape so that I can move in some new fish soon after.

Should I add ammonia so that the bacteria in my tank stays alive, and if so how much?

[ron v]

Add enough to get the test reading at 3. No more. You will need to that every day.

[DigiDan]

ok, so i read all this, and im a little confused, but is the purpose of cycling to create bacteria?

im so confused, you guys make it sound so damn complicated......

i need to take these things one step at a time....

are there ways to promote growth of the bacteria?
isnt there solutions at the LFS that help promote bacteria growth?