X2 on the sand! But I only have it on the poop boards and in the run. A poop board is a removable board under the roost that is big enough to catch all the poop that the chicken produce at night while they are sleeping(which is about 99.9% of all the coop waste). I just use a kitty litter scoop to clean the poop out of the sand in the am, put it in a 5 gal bucket and dump onto my compost heap. I have a container with sand and sprinkle more sand on the board as needed. This work great!
Oh and
From San Diego. I am sure you have input from the others but the feeds sold here in the US may be different. But I am Sure Purena is sold in Australia. Its a good place to start.
I'm from australia and feed wise I've had three breeders tell me barastoc pullet grower. I'd ask what the chicks are already eating when you pick them up and get the same product, would avoid any tummy upsets too