Hi, havn't been able to find anything on search about this:
I found some rocks that look like they would be nice in the tank, cept they have this weird reddish "rust" look to them. When I first washed them off, they did leave the water a little bit murkey but now it runs clear. Would the usual "fizz" test work on something like this? I would think not, how else should I find out if it is safe?