rocks in tanks, are they reef safe?

[nanopodreefer]

I just had a question about placing rocks in my tank. I know that with freshwater, one could take the desired rock and apply viniger/bleach on it. If the rock bubbled it was said that it may alter your alkalinity when placed in the tank. In regards to saltwater, is there a similar test? does the salt increase the risk of the rock dissolving? If so what does that bubbling indicate for a reef tank?

Also, the attached picture, was taken off the coast of Maui. Does anyone know what kind of rock the black boulders might be, and if I aquired something similar, would it be reef safe?

Thanks

[Rob]

these black rocks are likely lava rocks of some type, adn are not the type to keep in a reef tanks.

in a reef tank the best choice is to use reef rocks, these are rocks that formed on a reef, they are made of cacium carbonate, will likely dissolve or at least react in vinegar. they are made from the natural collection and compression of reef skeletons and other life. they are VERY pourus and light weight (when dry) and provide the ideal home for the anaerobic bacteria we need to filter or tanks

[Amphibious]

On the other hand, I've been a rock picker all my life. Just can't seem to pass up an interesting rock. Over the years I've gathered rocks from shorelines and cautiously used them. Most you find in proximity to the sea shore will be inert and not harmful.

[nanopodreefer]

Cool thanks, these reef rocks you mentioned, is that the same as base rock?, What makes these black rocks not reef safe, what will happen if I put them in my tank?

Amph - what type of rocks have you used?- do you have a pic of the tank you put them in?

thanks guys

[Raggamuffin]

The black rocks = cooled lava. They have no real calcium other then MAYBE trace element stuff, the problem is what else did that lava contain? sulfur? copper? mercury? diamonds? (last one was for kicks but ya get the idea) No single rock of that type will be like ANY other of that type when it comes to exact make up but the one thing they all have in common is at least trace ammounts of stuff you would NEVER want in your tank.

[Rob]

yea, base rocks are the same thing..
and as noted these rocks can be found on shores in the right place also, but you have to be cautious and know what you are looking for.

[fat walrus]

MHO, why play with fire?

[V]

All valid points, there is both possitive & negative views to these subjects. Ragga bought up the most valid point though, rocks of this type by there very nature are create at the very extremes where elements themselves are raw & easerly bonded with high temps,,time captuals for lack of a better word of a violent past.
A rock sitting in a large body of water like the ocean for thousands of years with at least some degree of matrix fractures should at least beg the question of wether there would indeed be anything traceable. The truth is every piece is different, & unless your testing for it or seeing an tell-tale impact from introduction who's really to know>?

the real kicker is going to be what your keeping, cause if its sensitive creatures, then the casual input of cool looking rocks would be off the cards compared to hardy mixed reef/fish only tanks. And another thing to keep in mind is because these rocks are formed under heat & pressure, theres only the outer surface area for colonisation of bactera to speak of & the displacement within the tank itself outstrips any benifits you might be seeking.

Laggon style tanks id say go for it, Sumerged reef seeting id say might be alittle too un-natral. & as blubber mentioned "why risk it"

[PSH]

MHO, why play with fire?

Or in this case lava.