Interesting. I hate to abandon coconut fiber when I have quite a large supply on hand, but if others concur it's risky I'll switch. I'll start thawing in bags anyways, it'll make things neater overall. Winter is the only time I even need my substrate to keep humidity up, aside from that it just needs to absorb some urine. Paper towels were a pain because they spread the urine over a large part of the enclosure. If I were to switch to chunks, what size do you recommend? Is there a different substrate I could use during high humidity months when I don't need it to hold moisture?