It is not required but I know that some people like to do an acidic rinse after they shampoo, especially if you have thick hair or a lot of volume. However, if you have coloured or thin hair it might not be a good solution. An acidic rinse can help to add shine to the hair and can replace a conditioner.
To make an acidic rinse, simply add 1 tsp. of apple cider vinegar in about 300 ml of water and use as final rinse water.
You can also make a rinse lotion by infusing Hibiscus flowers or Hibiscus powder, then strain. Hibiscus tea is naturally acidic.
Why an acidic rinse? The pH of the hair is quiet acidic 4.5 to 5.5 so it can be a good alternative to a conventional conditioner. However, if it's too acidic it can damage the hair.