Hi all, I use Arcadia Earthmix arid for my leopard gecko. Since it is not a bioactive Viv yet I have to change substrate. Today I opened up the new bag so I could air it before putting in Viv. There were two small holes and I thought nothing of it, yet when I opened it there was white stuff at the top that I have never seen in it before that looked a lot like mould. I quickly scooped it out and put it in bin. I waswondering if anyone knew what it is and whether I should buy new substrate and get rid of this or whether it should be fine.