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Tank cycling and maturation

Sep 16, 2005
Pittsburgh, PA
What is the difference between a cycled tank and a mature tank?

How can this affect a cephalopod?

It is my understanding (and I may be wrong) that a tank can cycle rather quickly (about one month with live rock) and have ammonia, nitrate and nitrite levels near zero.

I thought that the reason you are supposed to wait three months before introducing a cephalopod was to give the bacteria a chance to populate the live rock, substrate and other surfaces in the tank. Once the population of bacteria is high enough, it can handle (and convert) the waste that a cephalopod produces.

Experts, any input here?
Personally I think a cycled tank and a mature tank are similar but not the same. A cycled tank is a tank that has built up enough bacteria to remove the ammonia and convert it to nitrate and then convert that to nitrite and is usually referred to the first time one populates a tank with bacteria. However, once you add a lot of fish/ceph's your tank will take time to build up enough bacteria to handle this new amount of ammonia and nitrate. So you sort of have to cycle your tank every time you add a animal to your tank as the bacteria population in you tank/filter gets larger and smaller depending on how much food (ammonia and nitrate) it has.

A mature tank is one that is at equilibrium meaning that the ammonia and nitrate that is produced by your animals is being effectively removed by your filter (i.e. bacteria) and therefor is stable and you should not seen in large swings in you chemistry, usually in a mature tank there should be few new animals being introduced as this will cause the equilibrium to shift and it will take time to cycle or set up a equilibrium.

To answer your question about adding live rock. Yes, it will usually speed up the initial cycling process as will live sand. One thing that I've used in the past is to add substrate from a tank that has already cycled to the new tank therefor adding bacteria.

So thats my interpretation and if need be I could go into more detail but I've probably confused you enough.
Ok, I understand that whenever you introduce a new animal to the tank, the population of bacteria will increase to accomodate the increase in waste produced by the animal.

I guess my question is this, is a tank that has cycled (let's say in one month) ready to accept a cephalopod?
In a nutshell.

A cycled tank is normally a tank with no, or little livestock, which is new and has stopped producing positive results on ammonia and nitrite testkits. However, as soon as you add some livestock, like an octopus, it will start to show some positive results again and will take a few days to settle down again.

A mature tank is long set up, with livestock and has a balance between livestock and beneficial bacteria which normally wont show any glitches at all when new stock is added.

By 'mature tank' for cephalopods. i always suggested that the tank was stocked with fish, like mollys, for a few months. The amount of fish should be equivalent to the size of the octopus, or thereabouts so that when you get the octopus, you remove the fish and the bioload on the filter should be almost the same.

i.e. the filters are used to that amount of waste but this only works if you take all the fish out then put the octo in.

hope that helps?


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