What kind of rock is this?

[kampkomfort]

I was looking for some "dead" rock to add to my FOWLR 55gal. I have had a VERY difficult time finding suitable rocks at area landscaping firms, but I finally found one that sold ~40# boulders of "lava rock", or at least that's what they called it after looking it up.

It is a heterogenous gray/light gray color (some streaks of almost white), looks to be very porous, and is fairly "carvable".

PROBLEM! It floats, even after soaking it in a saltwater holding tank for several days. I also have noted that the pH in the tank hasn't budged (there is nothing else in the tank).

Is this actually "lava rock"? Any tricks for sinking it? I've pretty much exhausted my resources for anything similar, other than Aragocrete or the like. Thanks for your help.

K

 

[StirCrazy]

hey, looks like you have pummice.. a grey porous lava rock.. don't bother trying to sink it 99% of the time it will float forever.. you might be able to drill it and weight it down..

Steve

 

[clyde]

or bite the dust, order base rock from an online company or LFS - only way to really have LIVE rock.

Lava rock, I wouldnt even touch it with a 10 foot pole, maybe too many impurities in it, that will leach

BTW, you're in mississippi how can it be hard to find rock ? go down the gulf - there might be some LFS that sells 'TAmpa Bay Saltwater' rock

they're cheap and they're farmed rock.

or order from TBSW

at http://www.tampabaysaltwater.com/

[ November 14, 2001: Message edited by: clyde ]</p>

 

[Mouse]

Lava Rocks cool man, its man made, basically just clay thats been furnaced to hell. There should be no impurities, allthough many LFS wont garuntee this because the manufacturing process is unrefined, so technically yes there could be anything in there, but realisticly no its just fired clay. I think this excuse is used far too often because this happens to be the cheapest aquarum rock compared to Tufa or Reclaimed Rock. My current plan is to use the "lava Rock" as base rock. Basically im going to drill out holes in the rocks and slot them onto PVC pipes to create legs on which i can support egg crete to make reef ledges. I have encountered the floating problem in FW tanks which i have decorated with Lava Rock and after a year or so they do retain enough water to sink. Additionally the immense porosity of this rock should mean that once permeated with denitrifying bacterea should provide an excellent basis for filtration. Its also very malluable so moulding and drilling shouldnt be a problem, and its light weight too so thats another consideration thats a little less overbearing in the construction of your reef. Personally i'd go with it, just make sure you have the minimum requirement of Live Rock to provide ample Biological Filtration from the outset, and eventually the Lava Rock should become encrusted with Corraline algie and fan worms and be undetectable from the real thing. This conclusion was reached after a fairly long thread on the subject of converting Lava Rock to Live Rock. The observations and expiriences of fellow reefers lead me to beleave that this was a perfecly acceptable way of constructing rockwork and making your cash go a little further. We did however decide that curing, or at least soalking the rocks in a bucket of water, of a known chemical value(i.e. RO/DI), and then testing the water after a pereod of about 2-3 weeks to ensure the rocks were chemically sound would be a good idea.

Happy reefing