Difference: Established and Cycled Tank
- Thread starter James From Cali
- Start date
I think they are interchangable from what I have found.
These links all seem to talk about a cycled tank but use "established" instead.
(1) Understanding the Nitrogen Cycle: Part 3
(2) Vivid Aquariums Tropical Fish Store in Los Angeles - Beginner's School - Water Quality and Movement
(3) NAGARAJAN'S WEBPAGE FOR BEGINNER'S TROPICAL FISH AQUARIUM
(4) Cichlid Forum-Water Changes
These links all seem to talk about a cycled tank but use "established" instead.
(1) Understanding the Nitrogen Cycle: Part 3
(2) Vivid Aquariums Tropical Fish Store in Los Angeles - Beginner's School - Water Quality and Movement
(3) NAGARAJAN'S WEBPAGE FOR BEGINNER'S TROPICAL FISH AQUARIUM
(4) Cichlid Forum-Water Changes
A "cycled" tank is a tank in which there is, generally speaking, enough nitrobacter to metabolize the ammonia and nitrite in the tank.
Remember from grade school how you'd learn about the the balance of the food chain? How the deer would flourish, which would give the wolves lots of food, so the wolf population would grow, but then there so many wolves that the deer population would drop off and a lot of wolves would starve, which would mean fewer deer would be eaten, so the population would grow, and the process would start over again. Over time it settles out to an equilibrium, and the fluctuations all but disappear (barring any outside influence)
The same thing happens in your tank, just replace "deer" with "ammonia" and "wolves" with "bacteria".
There are a couple other fluctuations that stabilize after a few months.
In my opinion, an "established" tank is a cycled tank that's been running long enough to minimize those fluctuations.
Remember from grade school how you'd learn about the the balance of the food chain? How the deer would flourish, which would give the wolves lots of food, so the wolf population would grow, but then there so many wolves that the deer population would drop off and a lot of wolves would starve, which would mean fewer deer would be eaten, so the population would grow, and the process would start over again. Over time it settles out to an equilibrium, and the fluctuations all but disappear (barring any outside influence)
The same thing happens in your tank, just replace "deer" with "ammonia" and "wolves" with "bacteria".
There are a couple other fluctuations that stabilize after a few months.
In my opinion, an "established" tank is a cycled tank that's been running long enough to minimize those fluctuations.
Likes:
Seleya
I think JW described the difference very well! 
I know when I discuss a cycled tank, it simply means you have 0s and numbers in the right places. When I refer to an established tank, I'm thinking of a tank with some history and stability garnered over time.
A recently cycled tank doesn't tend to have much stability -- any challenge to the cycle is likely to throw it into a minicycle with little effort. An established tank is more likely to be stable through various challenges, even the occasional biggie.
I know when I discuss a cycled tank, it simply means you have 0s and numbers in the right places. When I refer to an established tank, I'm thinking of a tank with some history and stability garnered over time.
A recently cycled tank doesn't tend to have much stability -- any challenge to the cycle is likely to throw it into a minicycle with little effort. An established tank is more likely to be stable through various challenges, even the occasional biggie.
My understanding of the difference between a cycled tank and an established tank is that an established tank has been running cycled sucessfully for a few months.
A cycled tank should be safe for fish, but there are other biological processes going on in a tank that we can't measure.
Some delicate fish apparenly don't do well in a new tank. Perhaps the water is just less stable. Newer tanks also probably have small ammonia or nitrite spikes that our kits don't measure, so maybe that's it.
If you have a delicate fish that someone advises to only put in an established tank, be aware that it may be a sensitive fish. Definitely don't put it in a tank that isn't cycled.
Never put a new fish in a tank that is partially cycled. The partially cycled tanks have higher levels of nitrites and ammonia than one at the beginning of the cycle.
A cycled tank should be safe for fish, but there are other biological processes going on in a tank that we can't measure.
Some delicate fish apparenly don't do well in a new tank. Perhaps the water is just less stable. Newer tanks also probably have small ammonia or nitrite spikes that our kits don't measure, so maybe that's it.
If you have a delicate fish that someone advises to only put in an established tank, be aware that it may be a sensitive fish. Definitely don't put it in a tank that isn't cycled.
Never put a new fish in a tank that is partially cycled. The partially cycled tanks have higher levels of nitrites and ammonia than one at the beginning of the cycle.