Can anyone give me information about using Lava Rock vs. Live Rock?  A friend of my son's has had a tank for over 9 years of which he has used cheep Lava Rock to decorate his tank.  His tank is full of the usual Reef inhabitants and looks quite nice.  I have just started to put live rock in my tank (210) and I still have at least 195lbs to go.  So the prospect of using cheep Lava Rock is apealing.  But I would like to get the opinion of as many as you that I can before I start with the Lava Rock.

I've heard the rumar about lava rock as well.  Has anyone heard the same thing about lace rock?  (The stuff that they sell at most fresh water stores?)  I doubt that lace rock is aragonite.

In talking to differant people I have all sorts of things even about LBTR. 

One of the more interesting arguments was this:  Which sorce is more renuable LBTR or figi, or tonga take your pick live rock?  The person claimed that the ocean was more renewable then LBTR, will I think that he may be right, corals will always be growing and dieing, and just like anything else if it is managed correctly then we will have a renewable source.

I've heard the rumar about lava rock as well.  Has anyone heard the same thing about lace rock?  (The stuff that they sell at most fresh water stores?)  I doubt that lace rock is aragonite.

Lace rock is lava rock.  Unless you are talking about the white lace rock that comes out of central Texas.  I have some of that and it's limestone.  But the lace rock sold in the LFS is volcanic.  There's mountains of the stuff out in the west desert.  The local stuff is ryolite but "lace rock" might also be basalt.  Ryolite and basalt are very similar and differ in the amount of silica.

Porous black or red "lava" rock (called scoria) will leach ions into the water much more than light colored volcanic rock such as rhyolite.  Porous rhyolite is pumice.  Nonporous scoria is basalt.

The three dominant minerals in scoria are olivine, pyroxene and plagioclase feldspar.  Olivine and pyroxene are iron-magnesium silicates and plagioclase feldspar is a calcium-sodium silicate.  As a general rule, dark colored volcanic minerals (which make up dark volcanic rocks) weather much more quickly and thus release more ions than light colored volcanic minerals.

The three dominant minerals in rhyolite/pumice are plagioclase feldspar, potassium feldspar and quartz.  Potassium feldspar is a potassium-sodium silicate and quartz is pure silicate.  Rhyolite/pumice is very resistant to chemical weathering.

Scoria will leach iron, magnesium, calcium and sodium into the water.  There are also small amounts of nickel and chromium in olivine, which would also be released.

In conclusion, I wouldn't use any dark colored volcanic rock in a saltwater aquarium.  A white/cream colored volcanic rock probably won't release anything harmful into the water.  Live rock or Utah rock composed of aragonite is much better in my opinion.  Volcanic rock is often sharp and can cut fish if they run into it.  

Steve

B.S. Geology

I like to show off my geology knowledge once in a while.   Good luck with your tank.

 Awesome!

Geology is great!

Mark Peterson wrote: If you want to come along or want me to pick some up for you, you'd better call me quick.

Calling.... :-)

When I bought tank I have at my office it came with a bunch of Lace Rock.  This had been in the tank as a fish only tank for some 10-12 years.  Not knowing any better I put it back in the tank when I set it up.  It has been in there for over a year now and has coraline growing all over it.  Just within the last month or so Encrusting Gorgonia is also growing on it.  I haven't had any real problems with that tank because of this rock so I assume it's not leaching anything harmful.  This is the white, volcanic, lace rock that can be found out in the deserts around here.

Mark,

I used scoria in my first saltwater fish-only tank.  I had a lionfish, a green wolf eel and a grouper in a 90 gallon and nothing else.  The only drawback I noticed with it then was it would cut my hand if I picked it up too forcefully or it would scrape or cut a fish that accidenly bumped it.  Even though scoria weathers quickly compared to other rocks, it's still a very, very slow process.  A good sized piece should take millions of years to completely dissolve chemically.

Even though only tiny amounts of material are leached into the tank, I still not sure it's safe.  Dr. Ron Shimek's research on the extreme toxicity of copper (even in concentrations much less than 1 ppm) to marine invertebrates is frightening.  I believe chromium and other "heavy metals" may also be extremely toxic. 

A few years ago I set up my first real reef tank, complete with corals and lots of snails.  The tank thrived for about 6 months and then a problem started to apprear.  Some of my turbo snails, which had all been healthy since the tank was set up, began to become weak and fall over for no apparent reason.  This contiued to become worse until some starting dying.  At the same time, the coral polyps opened less and less each day.  After about a month, all the snails died and the coral polps remained closed.  The fish in the tank seemed completely unaffected.  My clownfish pair laid eggs throught the whole ordeal without pause.  All my water parameters tested perfectly and my copper testkit always tested 0.  I moved soon after the mysterious snail deaths and dismantled the tank.  To my surprise, the "stainless steel" hose clamp which I'd used to secure the tubing onto my mag-drive return pump was almost completely rusted away.  Stainless steel is stainless because of the addition of chromium and other metals.  I believe that the chromium released by the rusting hose clamp poisoned my tank.

I doubt dark volcanic rock would release as many toxic metal ions as my rusting hose clamp, but over many years scoria may release enough to affect sensitive inverts like snails.

I can stop by and look at your rock in a week or two when I journey south.  I'm not sure about my schedule yet.  The best way to test for trace amounts of copper in rock would be with an X-ray fluorescence machine or an electron microscope or microprobe.  I don't have access to them anymore.  If you pulverize a suspicous area of the rock and then completely dissolve it with an acid, it should liberate the copper ions into solution so they can be detected by an aquarium test kit.

Steve