Yeah... That's what sucks about not using substrate. I run a high output humidifier and a space heater in my snake room 24/7 and I keep the heater vent closed. I'm able to keep the humidity 50% - 60% in the whole room throughout the winter that way and I also mist every day/every other day (especially when animals are shedding). Definitely not the most cost efficient or easiest way to handle humidity by any means, but my house gets so dry during the winter that I doubt any substrate would keep the humidity levels high enough without still having to run a humidifier. I've been tempted to get some of this Reptile Prime and try it, though. Maybe at least I wouldn't have to run my humidifier on high 24/7. I'm mostly concerned about my animals swallowing it...