I had two geckos. They were in separate, but adjacent enclosures. One became ill and I found out it was crpto. I was very sad but she got put down.

My other gecko seems ok. He is larger. He eats and does firm poops but also does poops which are just pee. So I don't know if that means he is ill, or if he is carrying it but asymptomatic?
Will he die of it?
How can I stop him getting ill ?
How do I clean out the enclosure so it is safe to use again?

Thanks