I've always bleached new hardscape myself without issues.
I essentially soak in 1 part bleach: 10 parts water. Rinse really well and soak in dechlorinated water until the chlorine smell is gone.
You could always bake on low temp.which I might try doing..of course keeping a close watch!
Any particular mix for the dechlorinated water or just Prime by the directions?
Off topic, but is that a molly in your avi? Are the colors/pattern real?
WOW! That's a nice piece! What size tank is it going into?