# Why does Live Rock cycle?



## Greg_o (Mar 4, 2010)

Why does Live Rock cycle if it's coming from what I assume is an established tank at the LFS?

I understand it's acting to seed further bacteria growth in the new tank, but what causes the ammonia to raise? Does some of the living stuff on or in the rock simply die off during transportation?


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## 50seven (Feb 14, 2010)

Basically yes. The longer it is out of the water the more extreme it will be.

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## solarz (Aug 31, 2010)

Greg_o said:


> Why does Live Rock cycle if it's coming from what I assume is an established tank at the LFS?
> 
> I understand it's acting to seed further bacteria growth in the new tank, but what causes the ammonia to raise? *Does some of the living stuff on or in the rock simply die off during transportation?*


That's pretty much exactly it. There's also the issue of "curing". Live Rock from the LFS might not be cured.


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## BettaBeats (Jan 14, 2010)

tank parameters, lighting, etc.. die off then growth!


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## Greg_o (Mar 4, 2010)

Thanks for the responses - it's what I figured but was told at the LFS otherwise, should have known better.


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## ameekplec. (May 1, 2008)

Mmmm.....well.

Fresh live rock has a lot of die off and will need to be cycled - why? Because it's harvested from whatever sea floor, boxed up, and shipped around the world, often making a stop or two before finally reaching your LFS a few days later. So all that stuff on there dies, rots in your tank and needs to cycle.

If there's established LR, say at the store, or from someone's tank, as long as it's not out of water for hours on end and stays relatively moist (ie in a sealed tub or covered in wet rags/paper), there really isn't that much die-off in or on the rock, so you don't get an appreciable rise in ammonia/nitrites/nitrates, and thus no cycle.

So, moving LR doesn't necessarily mean you'll get a cycle. When I started my 10g, I bought LR from the store and didn't have a cycle since it was kept submerged the whole time until it got in my tank.


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## solarz (Aug 31, 2010)

ameekplec. said:


> Mmmm.....well.
> 
> Fresh live rock has a lot of die off and will need to be cycled - why? Because it's harvested from whatever sea floor, boxed up, and shipped around the world, often making a stop or two before finally reaching your LFS a few days later. So all that stuff on there dies, rots in your tank and needs to cycle.
> 
> ...


Hmmm.... depends.

Two months ago, I purchased additional LR from a fellow hobbyist. The LR went from his tank into my bucket (filled with his tank water), took a 40-min drive, and went into my tank.

The next day, I had a noticeable increase in Nitrates. Nothing major, and my nitrates are always at 0, and this raised it to maybe 10 ppm. Still, it's an indication that there had been die offs (most likely bacteria).


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## wildexpressions (May 3, 2010)

I have live rock in all my tanks including the stores fish tanks. When I sell rock I take it out of the coral and fish tanks because that way the rock is always very very alive. I also keep live rock in my plankton tanks.

What I have noticed is that I pretty much always see a mini cycle anytime I add live rock to a tank regardless of how well cured or aged it is. I'm not sure of the basis of this but I guess some life forms are so delicate that even being removed from water for a minute is enough, or perhaps it is the slight differences in chemistry that exist between any two tanks. I honestly have no idea.

I can take live rock from the back room that has been in my plankton tank for 3 months and place it in my main coral system, which has a sulfur bead denitrification unit on and typically no measurable nitrates, and I will see a small spike of +/-5 ppm that lasts for a day.


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## Greg_o (Mar 4, 2010)

This is all very interesting. Is the 'mini cycle' mentioned in the above two posts enough to cause harm to fish inverts or corals?


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## wildexpressions (May 3, 2010)

no, not in my experience but then both of us that are in agreement on this have stated that we typically have unmeasurable nitrates so a small spike of 5 to 10 ppm that last a day is not going to be noticed by most animals.

Most fish can easily handle long term nitrates in the 30 to 50 ppm and a great many show no substantial effects in the 80ppm range. There have been numerous studies, including some relatively long term ones, that concluded most fish don't show significant stress until the 80 to 100ppm range. Many invertebrates can handle much higher numbers then that.

Obviously there are some well known exceptions.

I'm not sure that I fully agree with those findings even though the studies methodologies and results seemed pretty clearly correct and accurate.

In my experience fish only tanks with high nitrates 40ppm+ tend to be slightly more aggressive. It is as if the inhabitants are just a little more moody and a little less tolerant of their tank mates indiscretions. While studies may be able to set a baseline and from there measure and plot the health of a fish how do we measure minor differences in a fishes mental state? 

Anyway, I'm rambling and getting off topic.


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