I have 2 goldfish in a tank with a filter, but i never did any type of cycling....what exactly is that? i read a few sentances of the link, and i'll read more later on as i've g2g for now, but is it un healthy for my fish not to have cycled it?
Odds are, the tank has already cycled itself. Tank cycling happens naturally in every single tank (with the possible exception of planted tanks, since plants can suck up ammonia like a sponge).
Cycling happens when you add fish to the tank. Fish, like all living things, naturally produce ammonia. Ammonia is toxic to fish.
In nature, there are bacteria present that convert ammonia to nitrite, and then nitrite to nitrate. In a new fish tank, these bacteria are not present yet. They need time to grow. So in a new tank, the ammonia just builds up until enough bacteria grows to safely process it. If it gets too strong, it will kill your fish. But if you clean out the tank 100%, you actually remove all the bacteria along with the ammonia. So you basically start all over.
There are test kits you can by to keep track of the ammonia levels. Once the ammonia level gets too high, you can bring it down by doing a water change. After about 2 weeks, the ammonia suddenly disappears. That's because the bacteria have grown and are doing their job. That's what cycling is.
One the the biggist "newbie" mistakes in fishkeeping is throwing all your fish into the tank at once. The resulting massive ammonia spike can kill them all. The best thing is do the cycling process with one or two hardy fish. The small fish amount will make sure that the ammonia production is minimal. From there, add additional fish one or two at a time.
After each fish addition, you may have a mini-cycle, where your ammonia goes up a bit. That's because the new fish are adding extra ammonia, and the bacteria haven't increased their numbers enough to take care of it. You have to allow time for the ammonia-eating bacteria to increase their numbers to compensate.
You can cut down on cycling time by "seeding" the tank with a few handfulls of gravel from an established tank. The gravel has bacteria in it, and will cut the cycling time way down.
Another option (and I think the best) is fishless cycling. It is much easier than traditional cycling. To fishless cycle, you basically add the ammonia by itself. Just buy some pure ammonia and add a few drops into the tank every day. No need to bother with water changes: there are no fish to worry about. Keep that ammonia level as high as you want! Just use test kits to keep track of the cycling conditions. When the ammonia spike is replaced with a nitrite spike, and then nitrate, you know cycling is done.
Another advantage to fishless cycling is that you can throw all your fish in at once without a problem. If you've added enough ammonia, you've grown all the bacteria needed maintain a full stocking level.
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