Originally Posted by jsalemi

Put a few drops of plain white vinegar on the rock -- if it fizzes, that means it has calcium carbonate in it and it's no good for most FW tanks because it'll raise the pH as the calcium dissolves. If it doesn't fizz, it's ok.

If it's not rated for aquariums, you need to boil the rocks or gravel for about 5 minutes first, to kill off anything that may be lurking in them. The advantage to getting aquarium gravel is that the manufacturer pretty much sanitized it before packaging it, saving you the boiling step.

Originally Posted by The Executioner

Hmm, so true about the aquarium gravel and I will listen to you to buy it instead of Home Depo gravels. On the other hand, is there any "Aquarium Big Rocks" as big as pond rocks?

Originally Posted by bandito974

I've bought river rock and other rocks at a local quarry for a very cheap price, The high calcium is good if you raise cichlids, so what kind of fish do you plan to Keep?