How fat are the dead that were talking about? My first thought would be they had swallowed gravel and died of a bowel impaction. It's fine to use underwater but your going to want to cover it with eco earth or something similar on the land portion. I've never had luck getting that type of setup to work the way I like. My favorite so far it to find a plastic tub that takes up most of the tank than pack eco earth all around it and fill the tub with water, filter, etc. Also don't use distilled water, use tap water treated with dechlorinating drops, like sold for fish tanks. Distilled water can leach minerals out of them causing imbalances in their bodily systems. It's okay for misting but not for soaking/hydrating substrate.

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