I may end up having to do that. When I first set it up, it hit 100%, but that was about 70% fresh substrate, with some dry stuff from the old tank mixed in. It has dropped off by about 10% each day since, so I'm waiting to see where it stabilizes at, but once it got down around 70%, I went ahead and moved him in. If it doesn't get down to 60%, I will add a few extra vents.