Hello, my husband and I are first time chick parents and seem to be at unable to agree on how often we should clean out the broodbox. He is of the opinion we should just add new shavings on top of the old, and "layer". I being an over protective mother, want to completely remove the old soiled shavings and replace with clean ones at least 2x a wk. I would be ok with the "layering" if they were out doors and we could crate a deep mulch system, but in a cardboard box there is no where for it to go. I am worried about illness. Since neither of us has ever raised chicks, I'd appreciate any suggestions. Thanks.