It's strange, but it seems that the strategy is always opening a connection to the default redis location: https://github.com/DatabaseCleaner/database_cleaner/blob/19773bbd1caa969e0e9be5eb0a8842b66f566f58/lib/database_cleaner/redis/base.rb#L25 It's a bit weird, as I don't see how to set the db parameter (which is not a db, but a url), and then, in the ohm adapter: https://github.com/DatabaseCleaner/database_cleaner/blob/19773bbd1caa969e0e9be5eb0a8842b66f566f58/lib/database_cleaner/ohm/truncation.rb#L9-L11 which is not used anywhere...