Really pleased with results!
The price is fantastic, also the colours: black and red.
I ordered 3 bags and I asked if is possible to send me big pieces.
I received 7 enormous rocks, because they are really light and porous.
Some of them I smashed with a hammer. Then I scratched them really well with a brush and washed with plenty of water. Just to be sure I kept them in water and bleach for one day, then rinsed them again well.
Also I poured some boiled water.
After this I kept them in water with a generous portion of Seachem Prime to declorinate.
I also smashed small pieces and stuck them in my canister aquarium filter. Good bacteria will find a good place to live in all porrous cavities. Don't forget to put them in a media bag, just to be sure to not let tiny pieces to run through filter and block your impeller from canister filter engine.
They are really good to stick plants on them with aquatic superglue.