Rock question

[Zen4t5]

I am doing some research on rocks for the aquarium. I want to get a 75 gallon in a couple months. I want to do mostly rockwork maybe, some driftwood. IMO, it is morally and ethically wrong to buy rocks from lfs and commercial stores. How much for the stuff that is free and is everywhere? I know the rock has to be inert. Is there any place else I can go for inert rocks? Is there any reasonable way to test if they are safe for the aquariums?

 

[Toirtis]

Go to your local landscape supply for the rocks, and you are looking for igneous and metamorphic rock. Testing is done simply with white vinegar...drip some on the rock and watch it for a couple of minutes...any fizzing/foaming suggests that the rock is soft and will break down in your aquarium over time.

 

[Zen4t5]

How much a pound do local landscaping usually charge? I know it changes depending where you are but I would love a ball park. Is the white vinegar test reliable? I have read it is not strong enough of an acid for some rocks. I have no problem going for a hike with a big jug of vinegar.

 

[blkwdw13]

I got all of my rocks for 25 cents a lb from the local landscape center.

 

[liv2padl]

you are looking for igneous and metamorphic rock

your average landscaper guy probably has no idea what igneous or metamorphic rock is. moreover, metamorphic rock can contain carbonates and silicates and thus is no guarantee that these compounds will be excluded from your aquarium. for example, Limestone will convert into marble with virtually any type of metamorphism. the main exception is hydrothermal metamorphism which introduces silica rich fluids, in which case the rock turns into calcium rich silicate skarn minerals. Dolomite minerals: CaMg(CO3)2

Testing is done simply with white vinegar

not strong enough in most situations to effect the release of CO2 that you're looking for as a test for the pressence of carbonate. you need muriatic acid. get it at your local building supply place.

fizzing/foaming suggests that the rock is soft and will break down in your aquarium over time.

well, i wouldn't describe it as 'soft' nor would i say it's going to 'break down' in time. what DOES happen is that any carbonate will be slowly dissolved by ionic and mineralized acid in your water. this process results in the release of carbon dioxide, a little heat and the leaching of carbonate into your water. this will have the effect of elevating your gH if the carbonate is in Calcium or magnesium form, the elevation of your kH through increase in your alkalinity (carbonate) and the elevation of your ph. the extent to which this can happen depends on your particular water chemistry. if you hve normally alkaline, hard water, the carbonate effect may be insignificant. if your water is normally acidic and 'soft', the impact will be stronger.

 

[Toirtis]

Yes, but I was trying to keep it simple. I was not aware that you could still easily obtain muriatic acid in the US.

 

[gotriceboy]

How much a pound do local landscaping usually charge? I know it changes depending where you are but I would love a ball park.

This is were I got mine.

http://www.lyngsogarden.com/index.cfm?fuseaction=showProductGroup&WebCat=STONE&WebCatDescr=

Here is my tank

http://www.aquariacentral.com/forums/showthread.php?t=80792&page=1&pp=15

For the type if rock I bought (New England Wall Rock) they charged me $.19 a pound. If a certain type of rock is common in your area, some landscaping companies may charge less. Good luck and post pics when you're done.