ADF Digging? Gravel + Sand?

#1
I have 2 dwarf african frogs in my tank, and they seem to be trying to dig and bury themselves inside the gravel. Is this normal? I want to get sand so that they can dig, but my tank is already established, and I don't know if I could add sand without harming the fish and frogs. Should I even consider adding sand? Or should I just ignore it?
 

Leopardess

Superstar Fish
#2
It's normal. Have you read this yet?

http://myfishtank.net/forum/showthread.php?s=&threadid=17868

They'd appreciate the sand, but it isn't necessary. If you'd like to redo it, you'd have to rinse the sand over and over again in a bucket until the water ran clear....and even then it'd probably still make a bit of a mess.

Have you tried reading the Sand FAQ? It's a sticky in either the Beginner forum or the general one, I can't recall atm.

If, however, the frogs seem to do it a lot, that can be an indicator that they dont' have any/enough hiding places like a cave made from aquarium safe rocks.