Avoiding Waterproofing

[zulu]

ELLO ELLO,
I am new to the forums, I have read almost all of these threads:P but was too lazy to click registar
I would first like to say I have a leo named Zulu (thats where i got the username idea ) I named him zulu because of his stealth and ambusing techniques he performs on his prey unlike other leos I have seen. Zulu as in Shaka Zulu the African warlord who used ambushes against his own prey.

Anyway

On to the question... I was thinking of making a grout background, I would like to have a waterfall built into the grout background but just to be safe I was thinking that sticking rocks such as granite slabs down the background in just a section. This 4inch section of granite is where the water will drip down, this way it will be safe for whatever species I choose to house? So basiclly a faux/real wall :P Is this nessacary? or can water flow down the side of grout or should I use concrete. or maybe even Habacrete (which i have no idea how to get a hold of)

[XtremeAaron]

I would recommend using Permastone. Heres my thread with a few pics to give you an idea:
18x18x24 Exo Terra Build Log

And here is the thread going through the discovery of Permastone:
Research to Find HabaCrete Alternative

As for waterproofing this stuff, really all you have to do it put a light coat of clear silicone over areas of water contact to help preserve the look and integrity of your background.