How long does live rock last?

[AJinNY]

I ask because I have had my tank close to a year and during that time I have notices tiny pieces laying on the sand that have broken off. Looking at it, I notice there are a lot more little holes in the rock than I remember. Looks good I think but eventually when enough pieces come off, I would think I would have to replace the rock OR maybe just rearrange things so there wont be an avalanche in my tank.

Those of you who have had tanks long term....have you added live rock over time or replaced rocks? Just wondering what to expect.

 

[DaveK]

My own reef has some florida live rock in it that is over 15 years old. You can have things like bristle worrms make new holes in the rock, and sometimes a piece can break. However, unless you do something to really damage or poison it, live rock will last almost forever, and is one thing that is always in demand by new people geting into this hobby.

I have added rock over time, but mostly because I got a larger tank, or wanted something on a special single piece of rock. Plus I have had my failues of stoney coarals, and the coral skelton has controbuted to the live rock.

Considering how much live cured rock costs, you might even see people leaving it to others in their will.

 

[EdgeKrusher]

The rock should last for a very long time, thouogh it will absorb alot of the nutrients and detrius that we don't want in our tanks. So I suggest blasting the rock with a PH or a turkey baster when you do your maintainance. This will make the LR more efficient, and last longer. Or you could do nothing and eventually have to remove the LR because it's saturated with stuff. I have also heard of people taking a couple pieces out every other year or so and boiling it, then letting it cure again, and it's like new.

Like DaveK said, there are creatures that do burrow through the rock so you will see new holes, and peices fall off. I wouldn't be to concerned unless you see that the rock is crumbling quickly.

Peace and Merry Christmas

EK

 

[Craig Manoukian]

Considering how much live cured rock costs, you might even see people leaving it to others in their will.

:bigbounce :bigbounce :bigbounce

 

[ScottT1980]

I echo everything that everyone else has mentioned, especially regarding the rocks as a nutrient sink. Also, the breaking away of LR pieces and the formation of new holes is not neccesarily a bad thing, as it adds more surface area for you biological filter to perform its services in your tank.

Take er easy
Scott t.

 

[Tarasco]

I was at a local reef club meeting where Bob Fenner spoke on this subject. According to him, you want to start replaceing old live rock with new rock after the first year. He said that this will help increase boidiversity, and will remove some of the bad nutrient build up that occurs over time. He also said something about the rock gradually breaking down, and losing it's effectiveness, since most rock is calcium carbonate based and it stops helping with alkalinity and ph as much(?). (not so sure about this last statement, it was a while ago). Anyways, he talking about gradually replaceing the rock over time. Just a thought.

 

[AJinNY]

Hey Travis. Looks like I asked another good question.....wheres my extra karma?

 

[DaveK]

I was at a local reef club meeting where Bob Fenner spoke on this subject. According to him, you want to start replaceing old live rock with new rock after the first year. He said that this will help increase boidiversity, and will remove some of the bad nutrient build up that occurs over time. He also said something about the rock gradually breaking down, and losing it's effectiveness, since most rock is calcium carbonate based and it stops helping with alkalinity and ph as much(?). (not so sure about this last statement, it was a while ago). Anyways, he talking about gradually replaceing the rock over time. Just a thought.

I honestly can't see why it would be required to replace live rock, especially after only one year. When my Florida live rock was new, I found new things living in it for the next 3 or 4 years. In this case I'm talking about things I'd never seen before. It just goes to show how much diversity there is in any live rock. I will say that adding new rock from time to time does add to the biodiversity. While this a good thing, I don not see it as a requitement.

I would also question the "bad nutrient build up". Live rock is going to have a lot of biological processes going on. This is why you put it in the system in the first place. I could see where it might be desirable to use a power head or turkey baster on it from time to time, as this would clear out a lot of build up you are likely to get.

As for live rock doing much for alkalinity or pH, this would seem to be limited. The biolocial film or coating on the rock would seem to limit the amount of material that would get disolved. It's not like a sand bed that may have been statred with new material, and also gets stirred up enough to get some clean new surface area to work with.

 

[Tarasco]

I wasn't really sure about it myself. I went onto Bob's website wetwebmedia.com to see if I could find anything out. Here's some stuff that he said:

"I do endorse adding, replacing part of live rock... to keep it's input in "dynamic equilibrium" (a fave oxymoron)... at about a year old, and then six months after... depending on size, type of system... ten to twenty percent or so"

"to add biodiversity, more readily soluble biomineral and alkalinity... a good practice after most systems are about 1 1/2 years old... to change out, add to their LR... a good 25% or so"

"The buffering and other mineral capacity is diminished as time goes by AND the biodiversity and abundance of the material wanes... so, at about a year and a half in use it's suggested that some be replaced or added to, and about six months intervals thereafter. Bob Fenner"

I found these quotes in his Live Rock FAQ's pages. I don't know if he has anything to back it up, but I thought that I'd point out that there's another opinion out there. Just something to think about.

 

[Woodstock]

Ughhhh... I could not imagine replacing 25% of my rock every 6 months. Removing 25% of the corals and then reattaching them does NOT sound like an easy job... And the cost!! yikes! I would go back to aragonite sand substrate before doing that; a hand full of new live sand for biodiversity then replace 1/4 of it every 6 mos. for more radily soluble biomineral, etc, etc, etc..... JMO.

 

[ScottT1980]

My only concern would be the binding of phosphates to the LR. Once a rock is saturated, then this PO4 could be readily available for algal use. This is one reason why people cook their rocks...

However, I have seen too many succesful tanks with 10 year old LR to make it a primary concern. PO4 can be handled in other ways...

I can't speak to a loss of buffering capacity or anything of that nature, because simply, I don't know...

 

[Woodstock]

I have 2 rocks I would like to cook right now. One is new base rock and the other is over 5 yrs old..guess ya never know.

 

[Craig Manoukian]

My tank has never been in better shape and the majority of my LR is 2 1/2 years old. I have added/deleted some rocks due to obtaining corals or fragging. I agree with Doni that as corals colonize it makes the task of replacing a substantial amount of rock problematic if not cost prohibitive.

Blasting the rock with a good water current to move detritus into the water column for skimming is a prudent endeavore for sure.

 

[DaveK]

I wasn't really sure about it myself. I went onto Bob's website wetwebmedia.com to see if I could find anything out. Here's some stuff that he said:
...snip...

"The buffering and other mineral capacity is diminished as time goes by AND the biodiversity and abundance of the material wanes... so, at about a year and a half in use it's suggested that some be replaced or added to, and about six months intervals thereafter. Bob Fenner"

I found these quotes in his Live Rock FAQ's pages. I don't know if he has anything to back it up, but I thought that I'd point out that there's another opinion out there. Just something to think about.

As a follow up to my own previous post, the statement made by Bob Fenner seems to be contridicted by Stephen Spotte in his book Captive Seawater Fishes and I quote -

What this means from a practical standpoint is simply that bulk minerals themselves (i.e., the minerals minus their overgrowths of magnesian calcite) do not disolve appreciably except at pH values below the tolerance limits of seawater fishes. In fact, at typical seawater pH values the opposite happens: the filtrants grow larger as magnesium carbonate precipates on their surface, not shrink from dissolution. ...

Any controversy that still exists among aquarists over which carbonate minerals are most soluble in irrelevant for two reasons. First, the solubility of a carbonate mineral depends on its surface composition. As just demonstrated, the aquisition of magnesian calcite overgrowths by all carbonate minerals quickly renders them indistinguishable in terme of solubility. Second, if the overgrowths did not occur, selection of the of the most soluble mineral would require detailed analysis of its composition and the composition of the liquid phase. "Standard" carbonate minerals and "standard" seawaters do not exist.

The book goes into an extremely detailed description of how carbonate minerals work in seawater aquarium systems, and would seem to indicate that changing live rock to buffer seawater would not be necessary.

I'm sticking with my existing 15 year old Florida live rock, except for adding a piece here and there for decoration. One downside of Florida live rock was that it tends to be more or less round or oblong balls, and it doesn't have some of the nice shapes some of the other live rock has.

 

[Craig Manoukian]

Thanks DaveK and Tarasco.

This illustrates the continual confusion and contradiction we face in this hobby. These forums are indispensible for sifting through the information and adding common sensible or experience laden viewpoints/input. Well done everyone!

 

[ScottT1980]

Yup, even the experts disagree...

I really see everything in this hobby as a cost/benefit ratio, whether it be DSB vs. BB, the salt you use, etc...

Take er easy
Scott T.

 

[mojoreef]

Great Thread. I dont think the buffering capability of LR is a big deal, IMHO something your not really going to get alot of anyway. As mentioned Previously the ph has to be low in order to melt it, this will happen in areas of the LR but by the time the carbonate gets to the surface it will have percipatated out.
On the nutrient loading, this is a reality, LR does not have the biological capability to keep up with the bioload we put upon them, also we dont have the flushing action that occurs on reefs or in the wild. Through bacterial action LR will shed detritus, but it is a slow loosing game compared to the input. Eventually the LR will loose tha vast majority of its nitrification capability to nutrient saturation. But this is not the end to LR it simple means that it needs time to regenerate or unclog. Cooking a LR (dark container with no light or feeding) will reverse the process, as in it will stop the input and allow the output (through bacterial action) to continue. This process however takes time, couple months. Recently I did a rescape on my tank and had several peices that were over 10 years old, they were clogged and were producing more nutrients then they were removing. I did not have the time to cook them so I put them in a big pot of boiling water and bioled them for half a day. The particular rocks I did this to went bone white and shed all of its detritus, back in they went and with in a month they were purple and repopulated with bacteria.


MIke

 

[Craig Manoukian]

Mike,

When you "cook" your rock to you use a power head, a heater or just salt water with no water changes? I know Curt just finished the process, could you explain the process in a little more detail? TIA

 

[mojoreef]

The concept is to allow for no more input Craig, so away from bioload. I put thm in a dark drum so thier is no more input from photosynthisis also, then just a power head and a heater to keep the bacteria and other critters alive.
Picture you rock as a huge apartment building for bacteria, never mind the larger critters that may live in thier. In order to consume or reduce products bacteria create enymes, they also reproduce, and die off and shed thier shells,this along with other this they do is what I am refering to as bacterial action or Tugor. With all of these actions they increase the biomass with in the LR. Because the LR is limited for over all space the end product this the accumulation of these products shed from the surfaces of the rock. In a normal tank enviroment all of these things are happening,but thier ia also a constant influx of food sources from the tank itself. The rock houses all the critters that are capable of reducing the nitrogen based products that enter it, but are restricted to the ammount they can do due to the population constrants do to the surface area of the rock. So its a loosing battle for the rock and pores and pathways get clogged with detritus and organics, when this happens it skews the enviroment with in the rock and turns it to more of an anaerobic enviro. Which means the rock begins to loose its ability to perform nitrification. The time factor is all based on husbandry and bioload.
When you place the rock say in a garbage can with no light and no outside food sources, you are forcing the rock to feed on what it has stored and clogged with in it, while all the time sheding the detritus or end product. The longer you leave it the more of this organic material will be consumed. the end result is that the LR will open up and unclogg it pathways and skelital features and thus allow for more surface areas for bacteria to grow and more open pathways for the food and various products to filter through the rock.

Oh and yes I use a PH, heater and I do water changes on it, I even run a skimmer on it to
Mike

 

[Craig Manoukian]

So you could cook a rock or two at a time and recycle the rock as ongoing maintenance/husbandry, or maybe carry an extra rock or two in "cooking" inventory, eh? Thanks Mike!