^yeah, just a regular rinse off, maybe a couple times in a large container. basically just to get the excess salt off (residual won't be harmful, its natural salts/minerals that may have their benefits) and any debris, chemicals and ghee (from kartik

) that may bummy your terapins' condition.
a good idea is to "buffer" the substrate-pond border with some smaller grained gravel (same depth as your substrate), this will help keep sand where sand is supposed to be and not get the substrate waterlogged with their in-and-out..looks nice too.
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|____Substrate__________|_Gravel___|__________Pond___________|
^like that when viewed from a cross-section.
fack whoever doesn't think my diagram hard..lol