Just use cypress. You get a big bag for cheap -- holds humidity better, doesn't mold from frequent/heavy misting, and is easier on the eyes
IMO. Also, it doesn't make all that yucky dust that aspen does. If you go with cypress mulch, just be sure a bake it for 30 minutes at 300 degrees to kill any bugs that may be living in the bag (same as you should with aspen). I got a big 55 gallon trash can and just dumped in there as I baked it until I was done and put it in the enclosures. I LOVE IT....way better than aspen,
IMO.
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BTW, don't get me wrong, I still use aspen in ONE of my enclosures, but its because I have a ton of it stored at the house and I'm just trying to use it up now lol.
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Sorry for the long-winded-ness......I'm kinda hyper right now for some reason.....