If you join on the groups and group_users tables as @simon showed, you can add something like this to your WHERE clause:
WHERE gu.created_at::date >= :since
AND g.name = 'trust_level_3'
AND u.admin = false
If you join on the groups and group_users tables as @simon showed, you can add something like this to your WHERE clause:
WHERE gu.created_at::date >= :since
AND g.name = 'trust_level_3'
AND u.admin = false