well, that rock came out of a guys tank recently. he had it in 2 bins and one of them had a foul smell....so i think at least half of that rock has some significant die-off.
some of the pieces have some zoos on them too, so i put them on top and added a 150 watt halide pendant i had laying around, which i will run at night to help keep the water warm overnight. this barrel is in my unheated garage and i haven't purchased any heaters yet. i'm relying on a hand full of power heads and that halide to keep the water warm.