zpool import/export help

[stratacast]

I have an external backup disk on my server with zpool "backups". I have numerous datasets being backed up by znapzend. What I would like to do is at the beginning/end of a scheduled task is to import/export my zpool. It seems however though when I run znapzend --runonce it tries to run the imports/exports almost all at once. I have this set up per dataset as a pre-send-command and post-send-command. Because of this behavior, I have import/exports disabled. Is there a better way to ensure a zpool import/export will only be ran once?