We have used both bark and apsen and like both. Recently, we bought a huge bag of exo-terra bark. I just wish I knew the free offer that came with it...lots and lots of free mites and a free (through the roof) humidity-booster. A few hours after putting the bark in the tank, Foster was in her water dish with hundreds (no joke!) of dead mites and the humidity was in the 90% neighborhood! This may have been an isolated problem with this exo-terra bark but I know I won't buy it again! And, before I forget, PAM works wonders and is worth every penny!