:hi guys. thanks for the replies on my first post last night. anyhow, i took your advice about replacing my calci-sand, but the only problem is i'm having a hard time finding aspen chips. i went to a few pet stores today and they only had reptile bark which consists of bark from a fir tree. they also had dessert mix which is made out of walnut shells that have been finely grated. are any of these two substrates acceptable for my corn?... thanks again! any help is greatly appreciated! oh, i almost forgot. i also have an undertank substrate heater. just incase it makes a difference on what substrate i should use. thanks again.