# How old is to old for live rock?



## jmb (Mar 20, 2012)

I have been looking at listing of someone selling Fuji live rock with purple coraline growth all over. They are selling for $3/lb; and apparently no nuisance critters. They say half is 5 years old and the other 15 years old. Obviously live rock is in the ocean for an eternity, but is this to long for a closed system

What's your thoughts?


----------



## Dax (Sep 29, 2010)

It is easy to say start with a fresh batch but obviously you are asking this because you don't have unlimited funds. Based on this assumption, IMHO, the best way to judge is to check the water quality of the system the rocks were in. If the water parameters are good then the rock should be good. Alternatively, put the rock in a bucket for a couple of days and check the water parameters; if they leach out anything, you should be able to pick it up . Usually the main concern is phosphates or residual copper.
Watch out for too much coraline as a heavy encrusting will "choke" out the rock.


----------



## poobar (Feb 20, 2011)

Never thought about it before but...

When I started in SW, I was told that live rock is very pourous and that is where the bacteria live and grow. My thought now, Is that isn't live rock much like active carbon, that is pourous??

But Active Carbon clogs up over time!

I have no idea if this affects live rock as well, but would like to get an answer.


----------



## wtac (Mar 17, 2006)

IMHO, I would be concerned with nitrate, phosphate and copper leaching from the rocks when put into your system. Bring your own test kits and test the water the LR is in .

LR and carbon are similar in that "what makes the magic" heavily depends on porosity. With LR, it's about having as much surface area for the various types of bacteria to colonize. You'll be suprised on how much "exposed" LR free of coralline algae is required for it to "do it's thing". With carbon, it's for elctromagnetic attraction and "trapping" it with in it's internal pore structure. Bacterial colonization does not impact molecular passing through to a great degree in this application. Once the pores are full of trapped molecular compounds, it's "exhausted".

Just a few tidbits from the ol' mellon.


----------



## Dax (Sep 29, 2010)

Hey, that sounds a lot like what I said. Well, when two people are on the same page, it must mean something.

Another way to look at the difference between LR and carbon is that you want to keep the stuff "trapped" in the LR in your tank and remove the stuff trapped in the carbon out of your tank.


----------



## jmb (Mar 20, 2012)

> LR and carbon are similar in that "what makes the magic" heavily depends on porosity. With LR, it's about having as much surface area for the various types of bacteria to colonize. You'll be suprised on how much "exposed" LR free of coralline algae is required for it to "do it's thing".


How do you think I can go about knowing the porosity? By simple observation and see if there are pits or does the rock feel lighter if it has greater porosity?

Thanks for your incite by the way.


----------



## msobon (Dec 7, 2011)

Poorus rock is a lot lighter once pulled out of the water to allow to drain vs dense rock per same size, you can also tell by which area the rock was brough in from. 

There's also the alternative of dried dead rock where you know it's clean and free of overything.


----------



## Dax (Sep 29, 2010)

Some things you can try:
-When you pick up the rock, see if it feels lighter or heavier based on what you'd expect? Not easy to feel, especially if it is wet.
-When you lift it out of the water, if it is seems like it drains forever that's a good sign.
-When you put it back into the water if it is releasing a lot a bubbles, that is also a good sign
-More theoretically, see how much volume of water it displaces for its size. The less the better.
- Make sure the surface is not heavily encrusted. Just scratch it and it should make a mark.


----------



## wtac (Mar 17, 2006)

This what you can generally expect Florida and Fiji LR to look like. If any pieces look like Florida or the dreaded Haitan or Caribbean, leave it with them. The latter two are ~25-40% heavier than similar looking sized Fiji LR.


----------

