Building paludarium, need help a little help

[LeilaNami]

So I'm in process of choosing my materials for creating my paludarium in a 55 for about 4 large, 2 medium leopard frogs. I'm trying to figure out what rocks to use and I know the rules for using them for fish tank but what about frogs? Say if I use limestone or marble, would the water hardness change be too great for frogs or native North American fish like dace? So far I have a list of slate, granite, quartz, and lava rock (not really liking it though) as my options. Any other rocks that would be safe for both the fish and the frogs?

 

[Mack&Cass]

For native fish, I wouldn't worry about limestone, many North American lakes are on limestone. Since your frogs are native I wouldn't worry about them either. Soft water (such as animals from the Amazon) species wouldn't appreciate the additional mineral content, however, should you ever change the animals in the setup.
Mackenzie

 

[Jaymz Bedell]

In theory any "wild" rock thats submerged in water full time should be pretty safe. in theory it's been in the water a long time, long enough to leach things like calcium out. in theory. slate and granite are great, even better would be rounded stones from a clean stream or river. allow to dry in the sun (uv is pretty good at killing things) and then scrub with a never used for anything but aquariums scrub brush, rinse, repeat as needed. then let it dry in the sun again. if you're really worried about the rocks causing a negative swing in the waters ph you can dust under the gravel with a tiny bit of peat moss, or add a bag of peat moss to the filter, and adding dried leaf litterto the bottom of the tank helps lower ph. leaf litter over gravel also gives the animals a place to hide thats a very natural.