Nah, bone dry inside. I don't know what the salt content of kiln dried sand is, but hopefully it's not a lot. It was originally meant to be a second system but is now my main due to a move and room size not really appropriate for floorstanders. I can't be bothered to empty and sort, far too much effort for comfort! I agree with you, I'm sure I'll be fine. 🤞🏻The stands must be hollow to allow you to fill them. Were they wet inside before you filled them? I'm sure you will be fine.