I've heard that potting soil really is bad, probably because it has that fertilizer rocks all over it. It never hurt my frogs, I've had them for three years. Then again, I have layers of soil that came attached to wild collected moss on top of the potting soil. Its possible they never had any contact with the stuff. I just put in a new plant (some kind of aroid if your interested, its a seedling I grew) and as I was digging a hole for it, I found myself with a layer of brown, muddy color, clay like soil. Under that was a mixture of potting soil and gravel. My soil has settled into the gravel bottom area over the years. This is my first viv, and the first time I have ever bragged about it so bear with me here. It was a spur of the moment construction when I brought home a spring peeper egg from biology class at college. I had no idea what the egg was gonna turn out to be, to my surprise and utter horror, the egg hatched in one night and the tadpole morphed in two weeks. I was totally unprepared. So I quickly took my old ten gallon fish tank, ripped off the glass section from an old light hood, and created the land/water viv!
Then, for some reason, i filled the land area with soil first, then with gravel on top. Put some Syngonium podophylum (the plant you see up there), and let my spring peeper morph. Except it had morphed over night while I was preparing the tank! Well, I put the tank + peeper in the window sill and fed the little peeplet tiny mosquitos that got into my apartment through the window screen. That was hard. In the end, the peeper grew fast, and died young from over exposure to the sun. I had this crazy idea i had to have the tank at 100% humidity so I covered the tank with a plastic bag in full sunlight.
The peeper didnt survive the summer.
Then I took the tank and inverted the soil and gravel layers to get what i got today. Plus got the idea that it would look great with lots of green moss. I did all this at the time believing I was the only one crazy enough to do all this for frogs. Oh well. Sorry for the lengthy story, hope its similar to someones story of how they started the hobby.
-Tind