# Rock ID...sponge?



## helgymatt (Sep 12, 2007)

I picked up these rocks at a local lanscape supply yard. 
I'm not sure what they are or if I should use them in the tank. 
From their website it seems they are either sponge rock or holey rock

Sponge rock...
http://www.rhinomaterials.com/photo_gallery/23.shtml
http://www.stonequestinc.com/images/spongerockboulders.jpg

Holey limestone...
http://www.southweststonesupply.com/boulders.htm
http://www.southweststonesupply.com/images/boulders/HoleyLimestoneB601.jpg

Anybody know anything about this rock or where it comes from? 
Would it be safe for my tank? I took them to the car wash and they had a lot of rust on them that washed, and washed, and washed. I think I got them pretty clean. And no, I didn't use any soap on them! I hope they wouldn't turn the water rusty. 
I would like to use them in a iwagumi scape. 
Here are the ones I found...


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## vancat (Nov 5, 2004)

check out this extensive thread:
http://www.thekrib.com/TankHardware/rocks.html


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## helgymatt (Sep 12, 2007)

Didn't get any fizzing with vinegar...


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## helgymatt (Sep 12, 2007)

People like this hardscape with these rocks? Suggestions welcomed before I do the plantings. Whats in there will be coming out and I'll be planting hairgrass, blyxa, and HC. Maybe a few other things.


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## chagovatoloco (Nov 17, 2007)

Try to scape with just the three big ones.


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## FrostyNYC (Dec 16, 2007)

If they were rusty, they're probably going to start leeching heavy metals into the water. Have you tested your gH and kH since adding those rocks?


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## helgymatt (Sep 12, 2007)

Why only three rocks? 

No I havn't tested the GH and KH. I'll test after a few days...just did a big water change. Not too worried about heavy metals because I do weekly 50% water changes.


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## HeyPK (Jan 23, 2004)

Those rocks should be fine as long as you don't want to maintain soft water.


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## chagovatoloco (Nov 17, 2007)

I think the smaller ones would get lost in the aquascape when it grows in, just an opinion.


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