I've seen coco coir is great to use, do you mix it with anything else and where do you get it? Also when using a plastic tote do you have to put a screen on top of it? Thanks!
With a plastic enclosure, the only reason to use a screen would be to protect the tortoise from outside factors; dogs, cats, birds, children, etc.
You could use a wide spaced hard wire screen to support a heat lamp but in most enclosures this would place the basking lamp too close to the tortoise.
Finding coco coir: check online and pet stores, and garden shops.