Ok so I'm downgrading from a 60cube to a regular 55 and was wondering if I could use the same sand I have in the cube for the 55 without causing any damage to my livestock, any major damage.
It depends on how long the 60g cube was set up, but normally it is good practice to start with new sand. I normally only save about two cup fulls to seed the new sand.
I use old sand all the time. Just put it buckets and rinse really well with a garden hose. I would NOT recommend taking it from the 60 and just adding it to the 55 without washing it first though.