systemd zpool scrub service and timer
You can use the systemd-zpool-scrub AUR package.
install -m 644 -o root -g root zpool-scrub@.service /etc/systemd/system
install -m 644 -o root -g root zpool-scrub@.timer /etc/systemd/system
systemctl daemon-reload
# enable for `tank`
systemctl enable --now zpool-scrub@tank.timer
# enable for every pool
for p in $(zpool list -H | cut -f1); do systemctl enable --now zpool-scrub@$p.timer; done