I got to an actual Reptile Shop. Over in England reptiles aren't really available at chain pet stores. They sell the products, and if you ask them will even say calci sand is good for leopard gecko's, so they aren't really in the know. My reptile shops breeds and sell reptiles. All kinds, including snakes, skinks, chameleons, monitors, water dragons, tortoise etc.
Even then, I back up their advice by checking with people on the forum. All I can say Vlad, is don't house the males together.
I was sold a "female" leopard gecko a while back. It was a sympathy buy from another pet shop that specialised in rodents and birds and aquatics. He was on calci sand, had no water, no heat mat, and was fed a cricket a week. He died of impaction after I became bonded with him. It was terrible. I will never step foot in that shop again. More disturbing was the reply from the local animal warden, who didn't want to do anything saying "there is no proof calci sand causes impaction".
I felt I had to do the right thing for the animals in the "care" of the pet shop, but no one would help me.