Who Gives A Fish Forums

I just added some awesome rocks I found to my tank, and I'm hoping you guys can help me out. I think they're "elephant skin stones", but they weren't labeled. The LFS staff said they won't affect my pH, but after doing some research, I'm getting a bit worried. Some sources say these stones aren't great for freshwater tanks, while others claim they're totally inert and super popular. I've even seen them in tanks with soft-water species, so I'm all confused.

Can anyone confirm if these stones are inert and if they'll mess with my water chemistry? I really love the way they look and I'd hate to have to take them out. My current parameters are: pH 7.0, KH 40ppm, GH 120ppm. My KH seems a bit low, but I'm not sure if that's a problem.

Thanks!

Quick update: I decided to run a little test on one of the stones. I scratched the surface with pliers and then poured some white vinegar on it - it's a weak acid, so I figured it'd be a good indicator. But, no reaction - no fizzing whatsoever. They do bear some resemblance to ryuoh or seiryu stones, now that I think about it... still, I'm stumped.

To get a better sense of how these stones might affect your water chemistry, you could try a simple experiment. Fill two containers with water, and put one of the stones in one of them. Then, test the pH of both containers every day - if you have the means to, also test the GH and KH. This way, you'll be able to see if any changes in the water are due to the stone or just the water itself sitting there.